If I were you, I would start just riding a bike with no structure at all. Some outside rides, zwift fun. Just for a couple of weeks to have a fun, feel the bike. Like during off season. After that perid test your FTP and start training. Yes, you don’t need to train to start training but why do you have to start the training from the very beginning? I was at the same boat a year ago after my crash and two surgeries. I have been riding my bike for the first 2-3 months just for fun. Mainly on my gravel bike. And I felt great. I discovered new routes, with no watts and heart rate monitor. Day by day I felt fitter and stronger with no structured plan. It’s a great time to re-discover why we started riding for the first place. But you can start a plan if you want. It’s not an issue at all. It’s all up to you 
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