A couple of things; I went solo unexpectedly when I was sent off by an instructor I hadn't flown with before. I think it was well over 12 hours - something like that anyway. Slightly numb with shock I did the pre takeoff checks twice (just to be sure) and really enjoyed it. Take your time and enjoy it as well.
Regarding the flare, I think we have all had trouble with this, but the best bit of advice I had was when a new Instructor said when we were on late final 'you are leaving it late and then having to rush sorting out the flare'. After that I rounded out more gradually and let the aeroplane settle level and it went well after that. I hope that makes sense. Have fun.