Bumble it’s peace of mind as well. When you’ve got that time your like “phew”, it’s still going ahead, it’s happening. Like it’s confirmation.
I thankfully got mine in the post like 7 days before or something like that.
It would be good if that was across the board. I’ve found a lot of folk (especially down south) have to wait till like the day before for their time. How frustrating!
If in doubt, phone, phone and phone again 
Patient Co-ordinators are usually really good at getting back to you though.
xx