So much this. I have seen a lot of guilds who promote officers immediately after just getting a few first members. In most cases, those very same guilds didn’t last much longer than a few months. In fact, I don’t think that any of the guilds that come to mind with this kind of officer promotion is still around.
Of course if you have a friend(s) who you already know and trust, and who’d fit the role and would want it, then that would be a great way to start out with an officer already in place.
Also, I would really think about how you also plan on recruiting members for it, and what size you are aiming for. I see people who will happily join large guilds that just send out mass macro-invites or spam trade, but some (myself for example) would sooner join guilds that are not based on mass invites and where recruitment is more of an individual process.
I just want to second this as well. It’s so important to have an online presence as a GM (especially in the early days/months as a guild) and therefore preferable that your main is in the leadership role. Most players who are considering joining a guild will want a GM who is active in the game. I was asked to join a person’s guild and I was confused because they had no guild tag, so when I asked what guild they were speaking of I was told “Oh that’s on a different character. I’m not really on her that much.” That’s definitely a no-go for me.
Edit: I just want to add this neat guild startup thing. It’s originally written by Bellatorx and aimed towards the Horde as that’s their faction, but it honestly is a great-great read and I’ve gone back to it more than once. It easily applies to any guild, regardless of faction.