Now, I know the title doesn't really do justice in what I need tips with.

DS - 2y4m - barely talks more than 2 words ('mumma' and 'again') but I've decided to start TTing him. We've started today and today only so far.
What I need tips and help with is, when do I know I should be putting him on the toilet?

Right now, this is what I do.
1) He has a drink, or something to eat.
2) 20-30 minutes after he's had a drink/had something to eat, I put him on the toilet for 5-10-15 minutes.
3) After said time, I'll take him off, praise him even if he's not done anything and let him go do what he wants to do.

Is there anything I can do to help me learn when he needs to go?
ANYTHING would be great!