Concerta 54mg to (temporarily) replace Dex 10mg?

Ok, I know this would not be recommended by my doctor. Situations is: dex 10 daily helps me hugely. But because it's taken me ages to get to this regular dose - and because on non-work days I often do without - I hadn't noticed my prescription has expired. Earliest appointment with doctor is 10 April.

But ... I have plenty of Concerta 54 from when I was on that a couple of years ago.

Anyway, you know what I'm saying.

Thoughts?

Thanks