I’m sorry to hear about your accident. I hope you are recovering well now. There are no simple rules for determining the length of any period of training. This is all dependent on too many factors. I suggest being very conservative, especially if you are coming back from and injury like this. At the very most I would start at the volume of training you were at the week before you got injured. It might be wise to start a volume smaller than this. You will know in a week or two if you have started too high.