It's not possible for a cheque to bounce instantly is it?
And even if it has, it may be represented automatically anyway, so you have to wait for the bank to tell you, not the cowboy.
1900 for a window is a shocking price.
Get the builder to down tools and stop work asap. Pay what you have to for work done, and make sure he doesn't darken your door again.
The home ownership scam should be avoided at all cost, and probably reported to the police.