353 gathering as of patch 2.4
My husband and I took 2 separate approaches to this.
He did Unearth II->Sharp Vision III on Node 7
While I did Toil->Unearth->Sharp Vision II, then Deep Vigor when it proc'd for a guaranteed HQ.
The difference being that his rotation gives a higher HQ %, but we all know that RNG is still just RNG so it's not a guarantee.
My rotation gave me a lower HQ %, but because Deep Vigor guarantees 1, even if RNG hated me, I still had one! (Often I still ended up with 2-3 HQ Umbrals).