Weaning from crumb to pellets?

[Rmnrgn]

Hi all,
A novice here. I hatched 13 embden goslings 2 weeks ago tomorrow and they're thriving on chick crumb. I also have them outdoors for a few hours a day on grass. The crumb comes in 5kg bags and costs 8 euro whilst the pellets come in 20gk bags and cost 13 euro. When can I start saving and moving them onto the pellets?
Thanks for the advice!

 

[Gray Farms]

I'd wait until at least 4-5 of age weeks.