Both options look fine to me — I'll leave it up to you.
You know this better than I do, so I'll leave it up to you.
I'll leave it up to you on timing — you know the client best.
I have no strong preference either way, so I'll leave it up to you.
I'll leave it up to you — just let me know what you decide.
Since you're leading this one, I'll leave it up to you.
I'll leave it up to you, but I'm happy to share my view if it helps.
I'll leave it up to you — both approaches should work.