For the most part, the order in which you do things is up to personal preference. The things your Summoner can do for your crafting classes, though, include unlocking levequest hubs, gathering mob-dropped materials, and unlocking access to the Ixali beast tribe.

The first two of those generally mean your battle class should stay around the level of your crafting classes, but the Ixali beast tribe is unlocked when you get to level 41 in the main scenario (after the "In Pursuit of the Past" quest) and is useful for crafting classes of any level.

(After that, the next big thing your battle class will unlock is access to the Heavensward regions, provided you have the expansion, but that won't be relevant until your crafting/gathering classes get through the first 50 levels, so it's back to keeping a battle job on par with your DoH/DoL.)