Proper work out questions?

i'm 18 and i just recently picked up working out again (i have in the past, but for some reason never truly dedicated myself to it, but now i am). i've been working out for maybe 3-4 weeks now, strictly push-ups because i'm conditioning myself for serious. at first i did roughly 5 or 6 sets of 20 a day; then 25, and now i'm at around 7 sets of 30 a day (with a rest day once a week). keep in mind i'm a beginner for the most part, although i have potential and some knowledge. however, due to certain cirstances, my work out begins at night and i spread the push-ups over a few hours, while doing other things (ending in the early morning - i've had sleep problems recently). my question is this...is working out during the night and then going to sleep detrimental to my progress? i see some progress but it doesn't seem enough for 3-4 weeks. i don't know, maybe 3-4 weeks won't yeild as much progress as i'm expecting, and i should just stick with it. also on a side note, i don't eat totally unhealthy, but i'm prone to junk foods (not an unhealthy amount). i also eat healthy though. but will these fatty foods also be a detriment? and also, i have a big bottle of creatine i haven't used yet because i'm waiting til i become dedicated. it says 5 g in a 8-10 oz drink...is that before, during, or after. answer all the questions as best you can and i'll give you the 10 pts