I wouldn't advise this, at all. Concerta contains methylphenidate, not an amphetamine, unlike Vyvanse which contains lisdexamfetamine. Amphetamines on top of amphetamines is not so much an issue, so long as you are being responsible with your dosing and listening to your mind and body, however this combination is a large issue, potentially, as the mechanism of methylphenidate differs from amphetamines, and in a way that could cause your body far too much stress. 21 hours is just not enough for amphetamines, considering their half-life; wait a few days - it will be better, I'd pretty much guarantee, as well as much safer.