I have only raised one batch of turkeys from day-olds, but also had some problems with them initially. They are now full grown and are laying eggs of their own, which are currently in my incubator. They are heritage turkeys (Midget Whites, Narragansetts and Bourbon Reds).
Like everyone says, they are really delicate for the first week or two. I lost about 1/3 of them (I started with 15); when they were about a week or two old, one was dying every day. I had been feeding them gamebird starter, but began giving them mashed hard-boiled egg yolk mixed with Greek yogurt as a supplement. I didn't lose any more after they were getting the egg/yogurt mixture, and they have done very well.