Need advice on installing paver patio

I recently removed a shed that had a cinder block and stone foundation. Haven't been able to get in there yet, but estimating it is 12"-16" deep. The research I have done says to have 7" under the pavers. Do I need to add fill dirt to get to that 7"? Can I keep the larger stones at the bottom under the paver base?

Any advice would be great, trying to do my best to not spend a ton of money but want to make sure it is done right!

Thanks in advance!