Adding and removing arrays from group

I have 2 x PS6010 arrays that i will be retiring and replacing with 2 x PS6210 arrays. Because i do not have enough room to delete the PS6010 i need to initialize the 2 PS6210 arrays first. My question is should i wait to delete the two 6010 arrays until the group balances out after adding the 6210 or can i go ahead and remove the 2 x 6010 arrays immediately after adding the 2 x 6210 arrays.