First I have to say Way to Go to the mom that replied before me, Early Potty Training Rocks!!!
I would defintely say keep telling him when it's time. This is such a new skill for him, let him get a handle on that first and then you can work on him telling you. If you think he actually has to go and is waiting for you to take him then just casually say to him "If you ever have this feeling that you have now (right before you take him potty) then it is ok to tell mommy and i will take you right away. Or you could even be a big boy and go all by yourself and surprise me" Just keep it casual, talk about it before he uses the potty so he can become aware of that sensation of fullness. But i honestly don't think most kids will Stop what they are doing to tell you they are going to go, just be glad he is dry. It is a very long processess so give him time and be happy with the small steps.
As for the night wetting, you could have him go before you put him to bed, then before you go to bed, slightly wake him and walk or carry him to the bathroom and put him on and see if he goes. He should go right back to sleep and possibly even sleep more comfortably, after a few months or so if he wakes dry you could play with the time you wake him and make him go, if he's dry at your bed time then maybe you just have to get up an hour earlier than normal and take him if he is doing it right before wake up. Personally, i wouldn't worry to much about the night training until he has been consistently day dry for 4-6 months. and limiting fluids at dinner and after also help with night training, just make up those fluids during the day so he doesn't dehydrate.
All in all you are doing a super job!!