I’m not 100% sure, but are you basically asking for a way to map a specific date (eg today?) to an interval (eg May 10 - May 20)? That is, the user enters a date (or its computed automatically from today() ) but what you want to actually record in the form is the interval this lies within?
If so, are these ‘intervals’ a fixed number of days, or per week, or per month, or arbitrary? (this may affect best solution).
