Those that are prescribed Elvanse + afternoon “top ups” - what time do you take them?

I am currently trialling 40mg Elvanse, (up from 20/30mg) and my dr said he’s happy to prescribe a 5mg Amfexa top up in the afternoon if I think I need it, as I felt the effects on 30mg waning too early around 2/3pm after taking it at 9am.

Now on 40mg (nearly a week completed on this dose), I think it’s in effect slightly longer but still not the desired length.. so what time would I take the amfexa? My ideal would be to have medication in effect from 8:30/9am through til about 6:30/7pm..