Sigilmancy (#19687)

You'd mainly have to go by who the most active chatters are. You could set up an application form on the Discord for people to apply for a spot in the first 15 (Leader+Founders take five slots), then pick the first 15 names randomly in a lottery, that would be fair.

Alternatively, if you really have that many people ready to go on Day One, make a second guild, a "feeder" guild, sort of a waiting room, where people can play and hang out while they wait to get into the main guild. Once everyone's in the main guild, you can dissolve the backup guild or keep it as a newbie application place / hangout / whatever.

It's not a perfect solution, but it does give your Guild more room to play on Day One, giving more people a chance to experience Guilds sooner.