There are too many variables which matter before you consider any calorie deficit.
Age, metabolic rate and background fitness. Structured training places significant stresses on your body and to ensure maximum adaption/ increased FTP means ensuring sufficient rest and nutrition to support and fuel your workouts.
Establish what calorie intake keeps your weight neutral and work from there but consider that the workload ramps up which means you need to increase your calories accordingly.
I’m 52 and aim for 1900 calories a day plus extra to cover whatever deficit is required from a workout. This translates to about .5lb a week weight loss but for SS1MV I saw a 46 watt increase.
So if you do incur weight loss it can be to the cost of not maxing out your FTP increases and whilst I’d like to lose weight my main focus is increasing my FTP. The weight loss can wait until I’m maintaining fitness over the summer .