Pre week 1 FAAB for RB?

I’m in a 12 team keeper league where waiver adds can be kept at the back of next years draft.

Someone in my league just dropped JK Dobbins. How much FAAB would you spend to get him? I was thinking 30-50%.

I think by mid season maybe earlier dobbins could see a huge workload. So I would feel comfortable with UP to 50% but would go above that.