Front wheel bearing service timeline ??

Thanks everyone for your feed back ,the front wheel bears are packed all the rear wheels are liq. oil bath . Cummin's coach care performs all my service , I recently had all the fittings greased and all rear wheels oil level checked .I did not have them check the front wheel bearings but maybe I should have .My manual does not state when to repack the front bearings .I'll contact my freightliner dealer to check their recommendation.
Thanks again
Gordy