HOW DOES IT TAKES FOR THE LOVEBIRD EGGS TO HATCH?

Normally, incubation period for lovebirds are around 21 days.  However, most of the times, it's not about when the first egg was dropped, but when they start incubating. A lot of the lovebirds may not start incubating right away.  And therefore, incubation period seems to be a bit longer. Normally, you can expect the lovebirds to hatch from 21 days to about 30 days.  After 30 days, if the any of the egg doesn't hatch, either the eggs are cleared or the babies already die inside. 

The babies can die inside due the fact that the eggs were not turned properly.  Normally, I do not allow eggs to hatch after days because, it's similar to babies that are premature. Those babies can turned out to have something wrong with them.  A rule of thumb is discard any eggs after 30 days.