Think about this logically.

If it were your first DSLR kit you might not even realize that you should shoot in RAW. Even if you do it will be a month or so before you find out you are running out of memory space on your computer. You wouldn't need a poll for that one.

If you bought a rebel kit that has a built in flash you could go a bit before you want an external.

Lens filter, if you bought a 5D III kit you might want a lens filter for protection. If you bought a rebel with a cheap kit lens I wouldn't.

That leaves Tripod and Bag/Backpack. I would get something to carry and protect my equipment first before anything else.

Tripod is a tool you should know you need / or do not need. If you are not sure you do not need it yet.

I go bag first for protection.