Buy-to-let mortgage - when do I move out

thecatwithnotail

Owner occupier of my flat, and I'm about to complete on a flat I intend to move to. To fund the purchase of this second flat, I'm remortgaging the first (I own outright) on buy-to-let.

So, the deposit is coming directly from this remortgage. I've been trying for a seamless a transition as possible, but haven't been able to pin down dates until now, when suddenly the vendor wants completion.

Main question (I have a lot) - is how long do I have to move out of my current flat in these circumstances. Realistically I think the answer is "you can't live there at all", but pragmatically how long do I have before it's suspect?

Really I'm thinking I'll be out in a few days/a week after completing - of course there will be some time between completion and exchange where I should be out but can't...

Anyone been in this position and can explain how it should work?

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EDIT spoke to solicitor, it's down to lender and mine will expect me out on the same day. Great.

Wh05apk

Buy to let mortgages are unregulated, therefore you will not be able to stay in the property, if you are asking would they know? probably not short term, but some lenders do now do further credit searches after a certain time, to check you have moved out.
Staying in the property could be construed as mortgage fraud if you were caught, so best to time completions simultaneously.