Hey All - seeking some advice around a training plan and when to start.

Quick background, riding about 3.5 years, had a year off, been more serious since October 2015, completed an 8 week intermediate century plan off Strava two weeks ago. I had a goal of a particular century event that I backed out of due to work commitments.

I am 38, and my historic main goal was to lose weight and be able to join/keep up with some local group rides and to be able to do a century.

What i was able to accomplish through those 8 weeks, however, is to be able to join my first shop / club rides and the expected weight loss.

Since the plan I was doing ended a few weeks ago, i have laid my weeks out like this:

Tues/Thurs 2 hour z2 rides

Sat shop ride. 2hrs z2.
Sun, excruciating to me club ride. 2.5 hours. This past Sunday looking at my HR, looks like all times evenly spaced across z1/2, z3, z4, z5

The event I want to train for is a hilly century, about 4k in climbing. I live in Fla so finding any kind of climbs will be tough.

12 weeks out puts me into the week of 8/20 to start a new plan (the century date is 11/20.)

However, work will have me on the road for close to a week straight (starts Friday 9/26) until that Thursday or so.

So am I better off pulling in a 12 week plan by a couple of weeks to time that week with an easy week? Or just lose out on that week?

Also, does anyone have any recommendations on a new plan to follow? I actually liked the progress made on the strava plan a lot and the simplicity of it.

Finally, no PM yet, still doing strict HR training.

Thanks!