I'm old school and the old school approach in this circumstance is to put in a lot of volume over the next 3 weeks with each week getting larger. If I can do it I like to do 15 hours, 18 hours 21 hours, but work usually gets in the way. It is called "base" or LSD which stands for "long STEADY distance" and not "long SLOW distance". You do that in such a way that you can survive a solid block of work (6 days) without needing a rest day, but after each day's ride you will want to eat a huge amount of food and take a nap.

After that cut back on the hours and ramp up intensity.

Other folks will disagree, and that if good. Training is not "cookie cutter" because everyone is different and everyone changes with age. Eventually you will need to figure out what works for you and your own personal goals.