New NAS Setup on SSD's?

[Enquiries]

Setting up a new QNAP TS-462 mostly for Plex Multimedia. Is it best to first install the SSD's as Raid 1 and set them up as storage and install QTS and the apps such as Plex Media Server on these 2x1TB devices? Then install the 4x6TB HD's as Raid 5 and setup the shared Movies Folder, etc. on the HD's? Or is it best to just install all the drives at once setting the SSD's in Raid1 as cashing and the HD's in Raid 5 and install QTS and everything on the HD's.

2 - SSD's are WD Red SN700 NVMe - 1TB each
4 - Seagate IronWolf ST6000VN00451 - 6TB each (Repurpose from non working QNAP TS=453Bmini)

Thank you for any suggestions you can provide...........Jose