Hi, @lisn. I had 8 rounds of Folfirinox, from April thru August of this year with an unintended three-week gap in late May-early June. Although everyone's experience is different, I'm sharing mine in case it's of use.

-- I too needed atropine with irinotecan; without atropine, I had stomach distress and bowel urgency. I didn't have any ill effects from the atropine.
-- Irin. also made me develop post-nasal drip for a few hours; it made my eyelids twitch during the infusion; and after a few infusions, irin. also caused short-term, intermittent spasming of my hands (a few ours to a couple of days).

-- My fatigue "schedule" was:
......... Felt worn out on Day 1 (infusion day).
......... Felt reasonably OK on Days 2 and 3 *but* didn't get much done because I was attached to the pump for all of 2 and part of 3.
......... Felt pretty good on Day 4.
......... Felt awful on Days 5 and 6: fatigue, nausea, no appetite, diarrhea. @markymarkfl, who is very helpful and knowledgeable, suggested that taking a steroid on Days 1, 2, and 3 could be the reason for this pattern. Days 5 and 6 were always my worst.
......... Felt a bit better on Day 7 and a bit better still on Day 8. During the 1st few infusions, I felt good on Days 9-14 and was productive.

****** Please note ***** that chemo is cumulative, meaning that the side effects could become more intense with each infusion (mine did) and that the number of bad days could increase with each infusion (mine did -- with my final two infusions, I had zero good days, although I wasn't _miserable_ for all 14). That said, I'm very glad that I took Folfirinox (my CA19-9 dropped a lot), and I'd take it again if necessary.

Good luck and best wishes.