Transfer from TalkTalk LLU

So I've placed an order for plusnet fibre extra. I'm currently in contract with TalkTalk fibre on full LLU. PlusNet have let me know that I can't keep my current number, which is not important as the line is only used for broadband.
At what point do I tell TalkTalk I'm leaving? My plusnet service won't go live for about 3 weeks and I don't want to be left with no broadband.

Any help would be appreciated.
Thanks, Steve.

Hi Steve,

It's dependent on whether TalkTalk have arranged for the cessation of your line or not. Would you mind messaging me your username so I could take a look?

Matty

If the voice line is going to plusnet that should trigger the GPL process, and TalkTalk will get notified of the voice move, and write giving the obligatory 10 day notice to allow you to protest to avoid slamming.

They should in theory keep the line active until it moves, unless someone told them to cease/cancel for a specific date.

Hopefully they will keep the connection going but it's best to be prepared for the worst with TT when you are leaving their LLU network