Order of Memory Cards When Adding RAM

I am going to upgrade my iMac 2017 27" computer from 16 GB to 32 GB by adding two more 8 GB cards. Right now the memory slot #1 and #3 are filled with 8 GB cards that came with the computer. Should I put my 2 8 GB new cards in memory slot #2 and #4 or should I move the existing memory cards to slots #1 & #2 and the new cards to slots #3 & #4?