Raising baby squirrels?

I have 3 baby squirrels I have been bottle feeding for just over 4 weeks. They were around 2 weeks old when they were brought to me. I haven't raised squirrels in a number of years and am trying to remember at about what age they should be taken off formula completely. They are eating some now (shelled nuts, cheerios, oats, etc.) but still rely heavily on their bottle 4 times a day. Right now, they are approximately 6-7 weeks old. I realize I will have them for quite a while still..just trying to remember how old they will be when they wean. Thanks!Raising baby squirrels?
how cute.