Keep checking the availability checker though as those brief "available" times you see are likely individual ports becoming available.
That was the 1st reply to this topic.
You did it, you ordered, the ports yours already. Nothing to worry about.
I ordered my initial FTTC service under the same circumstances.
My new build street was only showing as available to get fibre after the cabinet was full.
The BTWholesale checker changed back to waiting list within an hour or me ordering (about 3am).
I then helped neighbours order a service over the next few months. Each time the checker showed available some time after midnight, and changed back to waiting list within an hour of the neighbour placing their orders.
They all successfully had their FTTC activated on the expected dates.
I think you have nothing to worry about.