To me, that sounds like a very heavy commitment. I wouldn’t agree to it, if you were asking me to join your CAB. I asked mine for a maximum of 40 minutes per month on a personal or group call. It also matters depending on the seniority of the role you’re approaching. Managers usually think they have a lot more time than the C-Suite or SVP roles will think they have. People under-consider “future” availability, but there are psychological triggers when you say “bi-weekly,” etc. You can offer a minute-cap monthly, then allow them to self-select if they want to engage more. That’s how our CAB has worked .. one member who has taken it upon herself to be our advocate internally has already flown around the country for us, set up many calls, etc — she is putting in WAY more than 40 minutes. Others, it’s just a 30-min touch base every month.
In prior projects I've had some Advisors who have made it clear that they could not do more than 15min per month, while others have been available for 2-3hrs per week.
So depending on what you need/want out of them, make sure that you guys are on the same page in terms of expectations. Other than that it's wide open.