Previous supplier direct debit

Do I close my D/D with my previous supplier as soon as my bulb account goes live? I take it any outstanding balance will be billed to me once the final bill is issued?
Don’t want 2 energy payments coming off in a week!!
But also don’t want charges for a failed D/D… any advice?

Cancel your direct debit only once your previous supplier has confirmed your account is settled and closed.

Yes, you might well have two payments going out to two suppliers during your switching month. You won’t pay for your energy twice, this is just a cashflow issue and will be settled with your final refund. This is just a fact of life when switching supplier.