Usually it takes about a week from the time the eggs are laid to the time they hatch. Each day the egg color will change. The first day they will be bright orange if they are ocellaris. After that they will darken more each passing day till about day 7. Around then you should notice the silver eyes within the eggs and the eggs color will be a pale gray. At this point you can expect them to hatch that night or the following. If youre not sure and want to collect them all you can do is stay up about an hour after tank lights are out checking every 10 minutes or so. If they dont hatch, repeat the next night.