How do you plan on earning these miles?
Do you have any current significant mileage or points balances currents?
Do you have any current airline/alliance status?
Are you eligible for signup bonuses in any credit card programs? ie. do you already have a particular card that is only eligible for a once in a lifetime bonus? or a time restricted bonus?
While AS miles are generally a very good value for redemptions earning can be limited when compared to other bank and airline programs.
Planning for a December 2018-January 2019 now is good as you've left yourself time to earn miles and learn about how to search and redeem via the programs you choose.