One word of advice, don’t give up! I’ve heard it takes weeks months or even a year or so for some birds to start eating new foods. Persistence and routine is
key for birds. Offer the new foods at the same time every day, usually first thing in the morning as
@JayBudgiz said, they’re more willing to eat when hungry, but some birds aren’t willing to eat new food at all if they’re
too hungry. It’s all about what works best for your budgie.
Also, eat it with them! It’s bird behavior to eat together, and if they see you eating it they’re more likely to want to eat it, too. I had to eat my budgie’s chop to get him to eat it, it’s also a great way to bond when you eat together.
Offer the new foods prepared in different ways, some birds prefer their veggies finely chopped and others like it completely whole fit them to eat, some like it warm, others like it cold, etc.
Good luck!!