Is he showing interest in the toilet? Does he mention it when he poops or pees? Does he pull at his diaper, or act like he wants to get on the potty when you go?

If not, he's probably not ready. 16 months is awfully early to be trying to do it if there's no initiating interest on the child's part.

I think it is never too early to get used to a potty. Even if he isn't using it to actually go to the bathroom. Having him sit on it "like a big boy does", even with his clothes on is a good start. He will gradually learn what it's real use is for and want to start using it. When it looks as though he might be ready, try putting him in "big boy" undies and see what he does when he wets himself. If he is disgusted and embarassed, he is probably ready. If not, you at least tried and might want to wait a little while before trying again.

We bought a small baby bjorn potty and started our 11 month old on it. Whenever i put him on it he'll huff and puff and squeeze out atleast a few drops!. But, when he poops, by the time I remove his diaper and sleeper he would have finished it in the diaper itself.

I agree with both Becky and Haleysmommy...
Both are right on...
*We make the potty chair a part of the bathroom at around 12-13 months.*I have 3 boys. My first one was Day trained at 16 months, on his own initative..
My second, did not train, until about 3 months before his 3rd birthday(not that I hadn't been trying for over a year), but he was fully trained when he decided to. (that was the key to him...when I finally totally backed off and didn't pressure him at all, he decide it was time.)
My 3rd, is now almost 21 months, and he likes to sit on the potty chair, but has only peed in it once.

It's all about the personality and what they want really...

It's not too early to start talking about how Big People peepee in the toilet. You need to start at least talking to him about what is wanted. Let him know that Big People dont' wear diapers. He may decide that it is a good idea. Lead him to the bathroom and encourage him to at least try it. Get him to understand that this is important and that this is something that he should try to do. Watch him carefully and if he gives any kind of signal that he is about to wet or have a BM, then take him to the bathroom. Be consistant. You can't try training him one week and then spend a day or two doing other things and being too busy to keep on with it. He will get the idea that you aren't all that serious about it. Try before the bath, bedtime and after meals.

With little boys, sometimes the daddy has more influence on this than mommy does. It one of those "guy" things. If he is tall enough, standing up to pee sometimes works better than trying to get him to use a potty chair. Have a low stool or a thick book to stand on helps.

Just waiting for him to show an interest isn't always a good idea. Some children, particually boys just won't get the idea on their own. Why should they?? Diapers are handy things and they are not bothered by being wet or soiled. Using the Potty isn't on their list of interesting things to do. You really shouldn't wait. He may not get interested on his own and then you will be faced with a child that will REALLY be hard to train.

Developmentally-speaking, toddler's don't have the sphincter control to be independently potty trained until they are at least 18 months old. This is a physiological thing,not a pscyhological thing. Kids who are trained before then usually have pretty concrete bowel habits and parents pick up on their child's habits and respond to them. And even if they do have control at that point, it's pretty darn early to do 'official' potty-training.

But I would also say this..There is absolutely no harm in getting a potty and start playing with it with him. Many kids go through a stage where it's new and interesting. Let him sit on it, stand on it, put it on his head, whatever. Get that play part out of his system so that when things actually get more serious in that area, he's not trying to play with a 'full' pot! LOL! (I'll leave that to your imagination..:)

And if you want to start the using Cheerios for target practice thing, try that too.

Whatever you do, don't put too much juice behind the issue. Each child is ready when they're ready and go at their own pace. If junior responds, then great. If junior balks, leave it for another day. Go with the flow on this (pardon the pun please! LOL!)...