[cypher]

As long as the ham appears to be healthy & settling in ok, not unduly stressed I tend to introduce veg pretty much straight away, at least within a few days.
Very slowly though, try different things, small piece of one veg then maybe wait a couple of days then try a small piece of a different veg, the more variety they can have the better but just do it gradually.
If you want to change the main mix it's best to do that slowly giving a bit of the old & the new slowly increasing the new food if they take to it ok.
With healthy treats maybe just try one or two new things a week.