Charge when you need or want to (and for as long/short as you need or want to).
Ultimately, you are talking about getting three additional months out of a battery that only costs $70 to swap for new.
Battery University has detailed information to support the ideal being:
Do not charge above 80% and try to charge before you go below 20%.
Discharge 100% to 0% then leave plugged in until 100% once a month.