Your compabion's saying they need a rest, or even Tav themselves, has no correlation with camp events being triggered.
If you want to see as much content as you can on a single playthrough, the most rigid long rest timeline to follow is actually at the very beginning of the game, as most other camp encounters will queue up as expected once you get to the underdark/mountain pass and into act 2 and beyond.
In order to get the most content in act 1, follow this rough guide on when to long rest:
Wake up on beach -> long rest (optional, just an introspective Tav scene for cuisine race flavor. Personally I would skip this one as it doesn't make narrative sense to rest as soon as you wake up)
Collect Shadowheart, Astarion, Gale, and withers -> long rest after leaving the tomb you find withers in
Collect Lae'zel, introductory Grove goblin fight, Collect Wyll -> long rest
Talk to everyone else in Grove and do the rest of the Grove encounters, but especially Nettie, Zorru (with Lae'zel in party), and Sazza -> long rest
Collect Karlach -> long rest
From this point forward, you shouldn't be missing content as long as you take enough long rests through the rest of act 1, as the other scenes will start queueing up and aren't dependent on location/progressing further into the game.
