Definitely get the IRR first and build some IFR hours. Do the MEP course but don't take the test - if you do the MEIR course after that you'll have 21 hours to get the hang of things. If you really want an MEP rating, get it last. But it's really not necessary if you are planning to fly for an airline. Plan to have all that done by 185 hours, then you can do a nice easy 15 hours CPL training in a single.