I agree that companions should be somewhat front-loaded, but there is a risk of them being too front-loaded. I don't want all ~6-12 companions to be recruitable by the Druid Grove. The pacing/companion overload can handle maybe 1 more companion by the time we reach the Grove, so any others should be split throughout exploring the rest of Act 1 - overland main map, underdark, Creche, Grymforge - and maybe even into the beginning of Act 2.
Also, I want some companions to NOT have tadpoles. We could still find them in Act 1 sure, but it'd be nice if we had some companions with different motivations than "get this tadpole out of my head" or "learn to harness this tadpole's power without it taking me over."