At what age can I start feeding my baby budgies millet, fruits, vegetables etc?

As soon as they leave the nestbox.

I have millets and seeds in the nest boxes and the babies eat them when they are ready. At around 45 days they would be out of the box and eating veggies and fruits etc.

Thanks so much for the helpful info. The oldest baby is thinking about leaving the nest now but shes not to sure about it.