No idea, but when I take yohimbine HCL I take it first thing in the morning when I wake up, wait about 15-30 minutes, then either go to the gym and lift or cardio. When I ingest somethng, usually a BCAA-blend drink intra/post-WO, it has been a good hour sometimes 1 1/2 hours after I took the yohimbine.
When I take a second dose during the day I take it in between meals, sometimes 1 1/2 to 2 hours after a meal and/or 1 hour before a meal. I'm still experimenting with dosing to see what works for me - I may have to do a TKD-like diet where carbs are consumed close to workout time and all other meals are super low to no carb.
I know this doesn't answer your question, but hope it helps you in some way.