Rear main seal and valve cover gasket

I recently bought a 2004 Toyota Sequoia. I knew it had an oil leak. I sent it in for a comprehensive inspection and was told there were leaks from the valve cover gaskets and the rear main seal. I am going to do these myself, but it may be about 6 weeks before I can get to both of them. So I have two questions:

1. Should I do them both at the same time?
2. If not, which should I do first?

Thanks for your help.