IMO....it is a bit subjective. To get used to the bike and be able to operate it properly may take less than one month. I have known cases of ppl who had never ride a bike, bought a 500cc cruiser, learned it on the spot and rode home.
However, to really master the bike properly at all speed and road conditions takes time (from 1 month to more than 10 years even for some ppl). You may have to learn to discard you built-in "leaning phobia" and to trust your bike. It really depends on how fast you get comfortable with the bike, and not make "stupid' mistakes when starting out. Frequent riding helps a lot.
But everyone have to start somewhere. Go ahead and get the bike, learn to handle it and as a beginner always ride it at 70%-80% your current capability, and you will be fine to join convoys and gatherings. best wishes to you.