Congrats
If they are fertile they should turn darker in about a day.
Then you'll see them start to vibrate 2 days after that.
Don't be alarmed if they are suddenly gone... The parents often move them to a less visible area
If this is their first batch they'll more than likely eat them at some point... But at least you'll know you have a fertile pair.
Then you can do a lot of reading and set up a breeding tank