My budgie has layed and egg?

i have 2 females and a a male budgie and one of my females and my male hang out a lot. I found a egg in the corner of the cage today and i created a nest box for them and lifted the egg gently into it just once. My male and female have been chirping quite loudly to each other and I've been trying to get my female to sit on the egg.She occasionally goes near it but she won't touch it. I've put some lettuce inside the box, shes gone to eat it but she still won't touch the egg. Will we have to wait for her to lay a whole hutch until she sits on the egg? And is it okay that I've touched the egg just once because the mother is only about a year old and doesn't seem to be angry. Oh, and my other female keeps on trying to sit in the box but my male won't let her, (he chirps at her loudly so she goes away), does this mean the parents still care about the egg?