No way to say exact, different speed for different coats. My female would take a long time to fully grow back as her hair is so slow growing. My guess would be 6 months for her. I actually had her cut very short last summer and it was fairly long just before Christmas. But my little male would probably be grown out in a couple of months. His hair is the fastest growing I have ever seen. I have to watch out or he is walking on his long flowing coat within a month of being at the groomers.
I keep my Sadie pretty short as her coat is a little unruly, but Ben is floor length. Don't feel guilty about keeping up their grooming when your health was at stake. As long as they get their lovin', you can always catch up on the stylin'
Sorry you were so ill during the holidays, hope you are doing much better now. These little sweethearts can help with healing. Mine always seem to know when I don't feel well and are extra loving and attentive.