Pilot16, good topic you've choosen there. I agree with what the other instructors use as a guide (3 circuits without having to say anything), it all depends on how far the instructor wants to stick his/her neck out to get someone off first solo. Did you see the standard of the 6hour solo pilot? The instructor is not doing you any favors sending you off half ready. The last thing you need on your first solo is to have a big scare from something you might not have covered earlier. And as for flying when the weather is'nt solo conditions, make the most of your instructor's expierence to keep learning as you go.
Good luck champ, The 150 driver