I don't think it's too early to start on the plans. You could ask builders to meet with you to go over the plans to get an idea of cost and changes that could save on cost, but it's way too early to ask for bids.

I don't think it's too early. We are about a year away from breaking ground and we've met with 3 builders already. We're glad we did. It takes awhile to get a feel for each one. We knew what we wanted and had pretty good detailed drawings and a list of specifications. From that, we were able to get at least get a sense of which builders we would not want to work with. It helped narrow down the field. We worked with the remaining builders to fine tune our preliminary bid. From that, we'll choose a builder and work over the next year to finalize plans and finishes so that when we're ready, almost all the ground work is done. It took us over 6 months to come up with a detailed design, and we're still not finalized.

I wish that I had prepared further in advance for our build. My biggest mistake was that we found a lot and went right into the designing and building process almost immediatly. We basically made decisions for everything while building. I don't think you are too early to start the designing process but I doubt you would be able to get any bids so early. A builder would be able to give you an idea about where to save costs though if that is an issue for you.

our drawings took 18 months. too early? no way!

I am ahead of the game on everything as well. Go ahead and get bids but don't tell them when you are planning on breaking ground. Tell them you need to get a bid to make sure it's in your budget and that the "bank" needs an idea of how much this is going to cost. Then in your spreadsheet pad each bid by $1000 or so. This will help you out bidtime so you are on tract. Then when it's time to build call the contractor back and tell them sorry it took longer than expected but try to hold them to their bid price. Kinda play the game well if you want the job then it has to be at this price you gave me. Good Luck!

Not too early at all!
We started with a floor plan Jan 2008, and made many, many changes to it with the builder's designer (a very patient guy!!). Everytime we made changes, we kind of sat with the changes for a few weeks and 'lived' in the house on paper (if that makes sense). We found that having the time helped us greatly to think everything single detail out. We also made selections for fixtures, flooring, cabinets, and got price quotes from various sources. Only then (in November) did we sign a formal contract.

With our current home which we also custom built, we signed a contract too quickly and then once the build started, we incurred numerous costly change orders. We did not realize that we had signed on a very low bid for the home, with inadequate allowances for almost everything.
This time, we were well armed with what it would actually cost for all items. That way, we could discuss/negotiate with the builder before we signed on a realistic price for the home. So far, (we broke ground in nov.), there have been no plan changes or other finish changes (that would constitute a change order plus upcharge).

So, spend the time....if the builder truly wants your business, he should be more than willing to be patient with you.
And only after you are 100 % happy with the floor plan and all the various selections should you send it out for bids.
Good luck!

Here was our pre-construction schedule for a custom home using plans purchased on the internet but modified by an architect.

Old House prep for sale: start March 05, finish July 05

Find builder: Start June 05, found July 05

Drafting services agreement with builder and architect: Aug 05

Plans started: August 05, plans done August 06

Preliminary selections of all finish materials for refining budget: Aug 05 - August 06

House on market Sept 05, Off Market Nov 05, Back On Market Jan 06, Sold Feb 06

Move into rental: April 06

Grading plan started Jan 06, done May 06, Approved by County Juky 06

Contract signed: August 2006

Building permit submitted August 06, Obtained Sept 06

Financing obtained Sept 06

Hell Began Sept 06, Hell Ended Dec 07.

So it took us 12 months to get the plans done but the total prep time was much longer than that. Start now.

Good luck!

I second everything everyone else wrote. The thing that I did during this period that I am soooo glad that I did was to plan the actual placement of all of my belongings in the house. I made a few different changes to my floor plan when I realized that my belongings wouldn't necessarily work in the space that I had designed. On a couple of occassions, the "belongings" that didn't work were the dogs! It's a good time to make decisions about finishes for that reason. The other thing that I wish someone would have told me is that once building started, I wanted better and better finishes. However, on the things that I had already chosen the actual product (my laminate for example), I didn't yearn for an upgrade. With the other things (countertops), I came dangerously close to spending money I hadn't budgeted for and didn't have to purchased something higher-end.

My wife started working on our plans twenty years before we even bought the lot. Of course, she didn't start in earnest until we had the site. It took us nine months to get to turning them over to a builder. Ours is 100% custom however, so it took a while.

I think early planning is critical, but remember most people who bid on your project will say their bid is only good for 30-60 days due to such fluctuation in building materials. At least that is what happened with us. Good luck!

Get your plans drawn and engineered. If you have a builder or are interviewing builders, they will want an engineered plan.
Even if the builder demands a re-engineer, you will have something that looks serious and will get their attention.

Looking for land January 2000
Got serious March 04, house up for sale. Plans engineered. First bids by builder and subs for construction loan.
Sold house July 04. Moved in with mother in law.
December 04 Second bids or confirmation of original bids.
Closed on land and construction loan Jan 05.
Moved out of mother in law's and got an apartment Feb 05.
Started digging March 05.
CO issued August 05.

There is a bunch in between that can only be experienced if you build your own.

Peace