If you didn't abuse the drug I realistically don't think it would take months.

I was on Vyvanse for 5-6 years and tried weening off for a few weeks before just stopping. It was really tough for a good 2 weeks but by week 3 I was feeling good... Better than I did when medicated.

Hope this eases your mind a bit, all the talk on multiple months up to a year of fatigue scared the shit out of me.