Depends also a bit on the breed - my pure entire Shetland lambs (only one left entire this year as possible sire replacement in the flock) will stay with their dams until about 4.5 months old. Would take out a texel or other large modern breed a bit earlier. All my wether and female lambs are left until weaned naturally.
My goats have been in season already... one twice and regular! Not sure if the ewes are as early too - hope not!