Until your HVAC system captures it all. Check your filters regularly, and make sure you are using at least MERV 8.

cellulose insulation?
recessed lights?

Months I think. My parents second home (a beach condo) is still extra dusty. They finished construction several months ago.

You might want to wait to hang drapes, etc. My mom is convinced that some of the dust collected in her drapes (hung shortly after construction was complete) and they are the source of the problem.

We've been in 4 1/2 months, and I was just thinking the other day that the dust doesn't seem as bad anymore. We changed the air filters pretty often the first couple of months and used a stick vac on the wood floors daily. The place I noticed the dust the most, though, was in our 2 bathrooms that have dark stained wood cabinets. They showed every little speck. Now when I dust they actually stay clean looking for more than half a day.

"We have dark hardwood floors everywhere and it's driving me nuts."

Even when you don't notice dust on furniture, etc., you will ALWAYS notice it on dark floors.

Like mitri89 mentions above, they will be clean-looking for about ~1/2 day.

It will last for months, at least. We noticed the extra-layer of dust for almost a year. We don't have filters b/c we have a whole house air purification system instead, but we did clean that at 3X the frequency that was recommended by the manufacturer. My neighbors have changed their filters every other week for 6 months, and they still are experiencing the dust. They have extremely dark, almost ebony, wood floors though which cannot be helping!

I think that you will always notice the dust more since you have dark floors. As mentioned above, you would serioulsy need to clean them daily to keep the dust away. It's a pain. The worst for me is that there is no sippy cup in the world that does not leak, so I'm cleaning up milk spills hourly...which requires a full floor cleaning. :(

We had our ducts ( we have forced air) thoroughly cleaned by a newer company that claims to use a proprietary method more effective than traditional duct cleaning methods. Of course they cost more. Since then, the dust levels are more than manageable. His HEPA filter was caked so I can imagine what would have been.

He used a 5' tall vac cannister lined with prefilter and HEPA filter at the furnace discharge. He also cut an intake hole at the air return. A air powered brush with long shards of cloth was used to agitate the dust so it could be drawn into the vacuum. He drilled holes where possible so he could more efficiently route the brush.

Seemed to work well. It's not completely dust free but overall the job was pretty effective.

That sounds like a good HVAC cleaner.

I have severe allergies to pets and dust. (Listen up, all you people who just can't shop Home Depot or the local Mini-Mart without your dog beside you!)

After one severe asthmatic attack--stupidly gotten from helping a friend move boxes from her cat ridden house--I was going to move into a new home. When the HVAC cleaner arrived, I looked at his dusty hoses that were never themselves cleaned between jobs, and said, "Thanks. But no thanks."

Oh crap. I'll check my filters regularly and change them out. Part of the issue is that we haven't done landscaping yet and there a layer of sawdust in our garages and unfinished basement. We keep trekking the dirt in. The bedrooms stay clean for days but the main hall is dusty in about an hour.