As I said in a comment:
I do see one disadvantage with this: this increases the amount of time the Stack Exchange team has to moderate the site, as they have to moderate for the period between site creation and it getting its first moderators. I do have some alternative options which I'll propose in answers.
Alternative choice 1:
Use the old method of nominating moderators through a meta nomination thread
Prior to 2017, moderators of beta sites were decided through a question on the site's meta where users could post moderator nominations as answers, and Stack Exchange staff would select moderators from those nominations. For various reasons, I still believe this is a better system than the current method of elections especially when it comes to choosing the site's very first moderators, such as that it allows the Community Team to vet the nominees. However, the two key advantages it would have specifically for this site are:
It allows users to nominate other users, in addition to just themselves.
In a recent post, a Stack Exchange staff member said the following:
There are many viable election candidates within this community who we hope will nominate themselves for the position.
Everything hinges on that one word: hope that those who are suitable moderators will nominate themselves. However, in many past site elections, I've seen that many users who would serve the site well as moderators (as seen by their activity on the site) don't nominate themselves, as they don't believe they would or don't think they're cut out for a moderator position even if they may be (tl;dr they underestimate themselves).
The old nomination process allowed (and encouraged) users to nominate other users, or in other words, publicly state that another user is a good fit for the position. I remember running the initial pro-tem moderator thread for the Software Recommendations site, and at least one user who went on to be selected for the position said they initially didn't feel like they were suitable but changed their mind after seeing that another user nominated them. (They later went on to do great things for the Stack Exchange network; the Charcoal group that fights spam across the network would likely not have continued to exist if they hadn't been nominated.)
If we have lots of users who would be viable election candidates not step up because they don't feel well cut-out for the position, that of course creates a problem for the site's future. Rather than hope they nominate themselves, this process will allow other users to nominate them.
(Of course, the user would have to accept the nomination in order for it to be considered. In the above mentioned Software Recommendations thread, there were many who declined nominations because of time constraints or other reasons. I'm not suggesting changing this.)
There is no reputation requirement for nominees.
It might be possible that many users who would serve the site well as moderators don't have the 300 reputation required to nominate in an election. The old process didn't have a reputation requirement, meaning that such users could still step up.
I remember that two of the three users who went on to become moderators in the Software Recommendations thread I ran didn't have 300 reputation at the time they nominated themselves or got nominated by another user. (One of them is the one I mentioned in the earlier section.)
This would also alleviate concerns that some users who wouldn't be good moderators would just earn the 300 reputation required to nominate without gaining any real experience on the site at all, and would win the election by default if not many others nominated. In the old process, users who clearly didn't have real experience on the site could be picked up by community members or be denied the appointment by Stack Exchange, but this isn't possible with today's pro-tem election system.
This choice would involve canceling the election scheduled for August 29, and instead immediately posting a nomination thread just like in the old days.