Originally Posted by
nip101
I think somewhere around +3-4? Early on of course, I'm just now hitting 25x. It really slows down when you reach 5-6 area. Obviously if your gonna be afk for a long time, work/sleep you should try to get a longer game going to unlock various achievements. Also keep in mind you only seem to get more multiplier when you actually "upgrade" a girl and the higher up girls seem to give more.
Also I'd recommend saving all your diamonds for +10 time slots. Possibly the speed multiplier could be good to but honestly I think the slots are better.