Can anybody comment on the proper time/sequence in the construction process to pour the collar and the vermiculite bottom on a IG steel-walled vinyl liner pool?

I noticed a neighbor's vermiculite bottom is already in-place, but the collar hasn't been poured yet. That seems out of sequence to me (based on my own pool's building and a couple of other neighborhood pools I'd seen). I'm wondering if its worth bringing to the neighbor's attention?

My understanding (which may be wrong) was that the collar needed to be poured and inspected before the bottom goes in -- just in case the inspector (or even the contractors) noticed a problem with the walls/bracing. Any potential problems in doing the bottom before the collar?

TIA