In our school, adults skip the 9th kyu yellow belt, and instead go to 8th kyu orange belt. From there all students are the same. So, the yellow belt curriculum is a few strikes and blocks, and two basic stances. No patterns, just the very basics. It would be easy enough if you are actually a willing interested student, and not just going 'to see what it looks like' to get to yellow level in 7 sessions or so. Just know the rest won't be so easy! Also, we only have 2 tests per year tops, and we don't teach above belt level. So in our school we'd rather push you along the first one quickly so you aren't stuck doing low block/reverse punch in a front stance for 8 or 9 months. You lose students that way.
If it was 2nd kyu to 1st kyu in 7 sessions, then red flags would be exploding like the 4th of July, but white to yellow...if your instructor says you are ready I would trust your instructor.
jim