Help tapering 2 doses of Ambien/Zolpidem at night, which one first?

Hello!

I'm taking 10mg when I go to sleep, and about 4 hours later, when I wake up again 7,5mg again.

I started of course with 5mg, then moved up to 10mg, than 5mg 4 hours later when I woke up, and now I'm at those doses....    So I guess my body build up quite a tolerance.... I recently could't fall back asleep again from 5mg to upped to 7,5mg now for about a month. And my doctor always prescribed and said it was OK to go up, I never went up on my own... So now she said I have to wean off of course...

What is the best way? My doctor said we should start at lowering 10% every 2 weeks so that is normal I see here.

I can't make up my mind which dose I should lower first to do it right? I have begun at the first one from 10mg to 9mg for 2 weeks to come and then we will lower the second one for 10% or so and after 2 weeks again the first one. Is that right? Any advice?

Thank you very much in advance