I was thinking along the lines of building up to a blockbuster dose .
I wouldn't use that approach. You'll build up a tolerance, so when you go to experience a large, entheogenic dose, it'll take you a lot more shrooms than if you hadn't been building up.
My experience: I tried two entheogenic doses, J1 and J2, about a year apart, with other people there (J1, my guide and my ex; and J2, just my ex). I saw pretty colors, and it was entertaining as all get out, but neither was Earth-shaking. J1 was a considerably lower doseage, and served to reassure me the experience wasn't dangerous for me, so was probably worthwhile for that. J2 was considerably higher doseage. I then tried an enthoegenic dose, J3, solo, about five months after J2 This time
was Earth-shaking: major intuitive revelations, as well as the entertaining visual effects. I did another enthoegenic dose, J4, about a month after that; again solo. J4 was also quite emotionally powerful, but not as much as J3. I suspect because I had developed a tolerance from the trip only a month before.
I didn't log J1 or J2, but:
J3: 8 mushrooms, minced and steeped in hot water for 40 minutes. Ingested 2:30 after breakfast. Noticeable effects --aura, discoordination-- :10 minutes after ingestion. On the floor, non-cogent ~:29 minutes after ingestion. Beginning to return 4:30 after ingestion. 5:30 after ingestion, lucid, coordinated, very calm, still a bit wobbly. Completely returned 7:00 after ingestion.
J4: 9 mushrooms/1.175g; same preparation as for J3. Completely under @ :40 min. after ingestion. Beginning to return 4:10 after ingestion. Lucid and coordinated 4:50 after ingestion. Completely returned 6:30 after ingestion. Note the reduced durations of the shrooms' effects.
I then began microdosing, and for a while microdosing was amazing at reducing my anxiety, but after four months I had built up enough tolerance that I had quadrupled my dose to get the same therapeutic effect.
I suspect that the determining factor for J3 and J4 being so effective were that I was solo --I tend to be very self-conscious around other people, and need to remain in control of myself/the situation, which may have undermined my hopes for the shrooms. J4 was somewhat shorter in duration of effects from J3, I suspect because it was only a month after J3 and I was experiencing some tolerance. I am also nearly certain that the constant use of shrooms for microdosing led to a tolerance for them and their loss of efficacy at the end of four months.
All of which is to say that I would take the opposite approach to what you suggest: I would start with a major entheogenic trip and use that as a "loading dose" to begin microdosing a week later.
Here is the site I use to inform my own experimentation:
https://thethirdwave.co/