If she's 7.5 months, she is unlikely to need a nap 1.5hr from when she wakes for the day.
IIWM, I'd probably just jump to a nominal 6 month-ish routine and tweak from there, so something like this:
8 - wake, BF (even if BF at 5am)
9 - solids
11 - nap
12:30 - wake, BF
1:30 - solids
3:30 - nap
5 - wake, BF
7/7:30 - bath, BF, bed, to be asleep by 8.
Expect a bit of OT in the morning for the first few days, as it's a big jump, but you should find it settles down quickly. Much quicker an easier on both of you than extending 15 min every couple of days, you'll end up chasing your tail doing that. Once she's a bit stable in the routine, or you've had it going for a week or so, you should start to see signs that point to what tweaking the routine may need.
You'll notice I've left out solids in the afternoon/evening. These can cause digestive issues with LOs this young and cause night time disruption. Milk has more calories per ounce than any solids you'd offer at this age, so best off emphasising milk. Solids for tasting and fun til age one is the idea, providing you move along with various tastes and textures, you'll be able to notice any developmental issues along the way.
