HTB - Selling Property Redemption Process

juice_man

Hi!
My conveyancer has confused me as to how the Help To Buy equity loan redemption process works through selling my house and paying it back through the sale proceeds.
I have already had the RICS valuation and got the redemption information pack letter from Target confirming that this is ok and its the next steps I'm confused about.

My understanding from here is:-

1. Agree expected completion date along the chain.

2. My conveyancer sends legal undertaking email to Target (completion date must be this date plus 15 working days at a minimum)

3. 5 working days later target respond with authority to complete.

4. We can exchange at this point (as long as completion is after point 2 +15 working days). 

However my conveyancer has said this is not correct and has stated:-
1. They will request authority to complete 
2. Once this is received back (15 working days stated) we can agree exchange & completion dates.
3. We are free to exchange/complete at this point.

Does anyone have any recent experience on this?
Also any recent experience with the timings to get the authority to complete back? 

Thanks