'Normally' - meaning before the mad panic to order over the last couple of weeks - the ones that were not ready almost straight away were taking about 5 to 10 days. However, if you had ordered several wills there seems to have been no obvious order in which they were produced.
Thinking logically, a few days without new orders from the website ought to have allowed them to catch up with some of the backlog. Unfortunately, I know of at least one person who ordered 'several hundred' wills last week,

so the backlog could be quite large.