The best answer is as soon as possible. Yes, it drains the life out of you having to fill them out, but the sooner they are in, the sooner you will be considered.
Don’t rush and submit poor-quality writing, but don’t delay unnecessarily either. Start as soon as they send you the links, and do them in order to avoid having a bunch of unfinished looking over your head. I personally gave myself a week after recieving the link from a school to have it finished. It’s not unreasonable to be able to do 2-4 in a day especially if you have them pre written or can mix and match / modify from similar questions from other schools.
Ultimately, you only have to complete them by whatever their due date is, but sometimes late applications are less competitive depending on how seats are allotted.
Yes, it’s certainly possible to do 40 in a month, and August 1 isn’t a late deadline for yourself, but it’s not particularly early either.
