Raising a Digimon from an egg takes a lot of time, but if you use the Guild incubator, it can at least take a little less time than it normally would. Guilds can "Help" their members reduce that timer by 5 minutes per helper. To help, just "Visit" the Guild member, check their Guild incubator, and either help the egg or feed the In-Training Digimon some chocolate (neither of which come at a cost to you). Guild members are requesting help if their "Visit" button is highlighted with an exclamation point (!).

It's a little more tedious than just checking in or supporting your Guild, but it's probably one of the most helpful things you can do for each other. So make sure to check your Guild roster every once in awhile to see if anyone needs help.