Haven’t have experience myself but there was similar topic long time ago: Short intense period before starting base? Chad's short FTP boost plan - #5 by chad. Although nowadays modern way is probably using TrainNow and pick attacking workouts there.
Or even more cruel approach: How to Get in the Best Shape You've Ever Been In: Block Periodization - YouTube – take big bite in 1st week and then try to swallow it next 3 weeks