3 weeks (21 days) is average. But it partly depends on incubation habits of the parents, can be a few more or less days.
It's said that if the eggs haven't hatched after 30 days then they won't; they're dudds. You should wait until the hen gives up on them, though, before assuming that or trying to remove the unhatched egg(s). Typically the hen will decide not to bother incubating if they haven't hatched after about 40 days.
I suggest you get some good books, from the library if you don't want to spend money, about lovebirds' breeding habits and special needs when rearing young. They do need special care at this time.
It's said that if the eggs haven't hatched after 30 days then they won't; they're dudds. You should wait until the hen gives up on them, though, before assuming that or trying to remove the unhatched egg(s). Typically the hen will decide not to bother incubating if they haven't hatched after about 40 days.
I suggest you get some good books, from the library if you don't want to spend money, about lovebirds' breeding habits and special needs when rearing young. They do need special care at this time.