[Lovebirds]

i have a recent pair of garden doves they just paired up 2-3 weeks ago.how do i know when they will lay an egg.they are already sitting on nest.

Are you sure they haven't already laid?
Can't really predict these things. Rule of thumb is, approx. 10 days after mating........but that's not always the case. Some take longer and there's nothing you can do to move it along. Have to let nature do it's thing and be patient.