Working out when to migrate to UC, looking at my payments coming in prior

Hello,

I have to migrate to UC by a certain deadline.

Because I know that:
- my Weekly Child Tax Credit Payments
- My Fortnightly Housing Benefits Payments
- my Fortnightly Employment and Support Allowance
Will all stop if I do not migrate to UNIVERSAL CREDIT by a certain date, I am looking at my calendar and planning to migrate after my last Housing Benefit payment.
My migration to UC notice says my CTC, HB AND ESA will stop if I do not claim UC by a certain date.

The letter also says CTC will stop from the date I make my UC claim and the other benefit payments will stop 2 weeks after i make my claim.
- Is the date I made my claim the final day I sent it ( even if I took days or weeks to do it a bit at a time?)

- I think I recall I read somewhere that I can start migrating to UC and have 1 month to finalise the migration from the time I started.
I do not know if I am correct for sure because it is not written on my migration notice.

1) Is it the case I have 1 month to migrate from the time I start the claim online?

2) I assume that if so I can save my claim form online?
Or has anyone saved the info and the information was not saved and we had to start from the beginning again?

3) does anyone know how long it takes to migrate if we do it in one go approximately.

4) is it lengthly to do and do we have to provide evidence like proof of my ID?
Do we have to provide proof of ID of our children?
I would have thought they have all information already,

5) does anyone know if it is easy to get through to Citizens Advice Bureau for them to help us migrate, hopefully we can get a bit of help at a time, rather that doing the migration in one go.

I really appreciate you sparring the time to help me.
Thank you.
Best wishes