Eblex' advice assumes that the pasture is under pressure, and makes sense in that scenario.
If you have plenty of grass, I'd have thought that the check from weaning would be best avoided. Most people reckon that a lamb will stand still for two weeks when it's weaned.
2 weeks is a long time if you were hoping to get it away at 12-14 weeks!
If grass
is under pressure, I'd be inclined to think about speaning twins earlier, perhaps, as they'll take longer to fatten anyway, and try to run the singles on with their mothers until they're ready to go - no check, away soonest
I'm talking lambs that will finish in one season, of course. A completely different equation with lambs that take a year or more.