I wondered whether you'd recommend that I starting preparing now.
If so, how would you change it?
Without more context it's hard to assess. But, standing alone, the tensing seems awkward to me. You're saying you "wondered" in the past, about something involving the future (whether you "would"). If it's yet to be determined, why not say "wonder?" If everything is now a past event, then why would it really matter now?
You're still confused, layman. I'm not "Perry".
I wrote a similar sentence to an employer, and im stressing out about it. I think the sentence would be better without the that?