Numbert port before contract ends

[Emalucy]

Number porting advice
I took out a mobile phone contract with mobiles.co.uk and the airtime and phone costs have been paid by D/D to O2 I texted for a PAC code as my contract ends in 6 weeks and also texted for a balance i would generate if i used that PAC code.
I was happy because it meant i would only pay an extra £10 extra on the normal cost of my monthly bill if i used the PAC code.I went ahead and gave the PAC code to my preferred network
I am now worrying because O2 have disconnected my sim and the sim on the network i was porting to is still linked to its original number.
Will i have to wait until my final balance is actually paid before the number port will complete.
O2 will be paid by D/D as soon as payment is requested .Thanks for sny Help

[MI5]

@Emalucy 

The transfer will happen as soon as your new network processes the change.

O2 will generate your final bill so don't cancel your direct debit until it's paid.