When Does the Bonus Clock Start Ticking?

Hi, I’m going to sign up to drive for Uber and Lyft soon. I plan to start driving at the beginning of the new year. Should I sign up now or wait until closer to then? I’m worried about when the clock starts ticking for the bonuses such as xx drives in your first 30 days.

Is there a good thread or doc somewhere as to how to optimize signing up and getting started on both Uber and Lyft for a newbie? I already have a referral code from a driver I like in both companies.

Thanks in advance for any help.