The use of stills cameras is the better idea you can find. Take that recomendation…By other side I thing in a 3 months timelapse a frame per second looks too much….I don’t know what will you film…but if it is a construction or some like that yo must calculate what you want….by example in three months you will get near 8 millions of seconds (and frames or pics)….near 8 millions of frames or pics at 30 fps means around 260,000 seconds of movie or 4,320 hours…I know i am drinkin’ at this moment…but
regards