It’s whatever works for you. The majority of my fat lambs go straight off their mothers, but anything left by mid July is weaned (I lamb end feb/beg March). The ewes need time to get condition back before the rams go in, and I have access to grass away from home that they can graze. The lambs and any cull ewes stay at home where they are handy to bring in to weigh and pick out fat lambs.