When do I declare auto-entrepreneur turnover when set up as a business in France?

I am about to set up as an auto-entrepreneur following your advice last year (thank you!). I just want to check a couple of things:

1. I want to set up now so that if I am offered work in February/March I’m all ready to go. However, I may well have a few weeks before I have any income to declare. Will the auto-entrepreneur authorities accept this? I am guessing I would just do a declaration three months after the start-up date of whatever I have (or have not earned), is this correct?
2. I also have a flat in the UK which is rented out as a holiday let. I declare this in the UK but after deductions for allowable expenses I only make a very small profit, on which I do not need to pay UK tax. At what point do I declare this small profit to the French authorities? Do I need to do this at the very start (info from previous tax years) or do I do it after one year?
3. I also may (as yet undecided) have some dividends from a UK Limited company - again, at what point would I declare these dividends to the French authorities?
4. I understand I am legally obliged to declare all my Uk bank accounts to the French authorities. I have a couple of dormant ex-ISA accounts, one with zero amount of money in and one with 17p, and a small UK building society account. Should I definitively close these accounts before registering as an auto-entrepreneur or would it be OK if there is an overlap of a few weeks? I will not be in the UK until March and I think I may need to be there in person to close the accounts.