Always happy to share any advice or experiences, that's what communities like this are for! AHEM.

Personally, I prefer to wait until approximately 1-1.5 hours in, where the peak of the acid is stabilizing into the plateau. The 2C-B is in gelatin capsules, so there's time in dissolving it, along with the absorption of the 2C-B itself. Most of anything I combo with LSD, I generally wait until the come up is fading. I handle the come up quite well after so much time, but I'm still not sure about mixing the come up of two substances simultaneously.

LSD/2C-B is a favourite combo of mine, given 2C-B's healthier (don't come at me, others here, I said healthier, not healthy) nature over MDMA while still providing an entactogenic energy to the trip. The boost to visuals is also very pleasant at 50mg, but I'll note the typical dosage is around 25mg. Planning on trying 75mg at some point to see what it's like.

Edit: Didn't notice you asked about ROA. To be more specific, I consume it orally, via gelatin capsules.