Most Helpful Girl
7 months is long enough! Just go for it.
Most Helpful Guy
i'l tell you how. At least im glad you did do your move on the first girl so you do have the courage.
If you two didn't have much eye contact before, try to exchange more eye contact with her. If you two already make a lot of eye contact, that's great (its a good sign). Try to make her feel like you are attracted to her or find her attractive; for example if one day she was wearing something sexy tell her jokingly 'you are not allowed to wear that infront of me anymore' if she tells you why tell her its too sexy OR i find you too attractive in that. You can also add that it gives you dirty thoughts or that you might lose control or kiss her (depending how close u guys are).
from those you can get signs from her reaction or body language if she likes you or is starting to consider you.. etc. You can do that, or just go for the talk or 'ASK OUT' a couple weeks later.
I personally like to confront the girl and go all out, especially if i was friends with her before and know a lot about her and liked her.
A tip for your future, don't just be 'friends' with girls. try to minimize that. I do have female friends but i make sure i make them all know i find them attractive (yes almost all my female friends are attractive), so if i asked one of them out they won't be surprised because they already knew they are desired.