@lynneblundell My kids were all about three when they got their first bikes. Small, with training wheels (which is what I think you must mean by stabilizers?), and easy to manage.
The hard part is waiting until they get the hang of pedaling. It’s one of those things that just has to “click.” If your son hasn’t had a tricycle or some other kind of pedal-powered toy, it might take quite a few tries before he suddenly gets it. I think practicing inside is a good idea, and then once he has the pedaling motion down, take him outside. He’ll go very slowly at first, which will make it easier for you to walk along beside or behind him. He’ll probably need a little push to get the bike moving. Even with training wheels, they can tip over if they try to turn too hard. He’ll probably look at his feet instead of where he’s going, and you can be right there to help guide him. He’ll have to learn to steer, which is another thing that kids just have to “get” before it becomes second nature. You’ll probably remind him seven hundred and twelve times to watch where he’s going and not turn too fast. :)
My youngest was three the summer before last, and spent several weeks practicing on his bike, off and on, but never really felt confident enough to do more than ride in a straight line for a while (after a push from me to get him started), get off, turn the bike around, and ride back the way he came. This past summer, he did much better. He could ride all around the driveway without a push from me to get going from a stand-still, rode in circles around my car, and figured out how to break by pedaling backwards. He liked for me to ride my bike around the driveway too, so he could follow me. A huge difference from last summer!
Just give your son time, and if he gets frustrated or tired of the bike, let him take a break for a while. Odds are the bike won’t be too small for him for another year or two, and by then he’ll have the hang of it. Once he really gets going, probably age 6 or 7, he won’t need the training wheels any more. The time frame just depends on his own level of coordination and how much practice he gets. My other son took a bit longer to be comfortable on a bike, while my daughter has been biking like a champ since she was six.
Have fun!