if you have to wait another week or so for the injectors I would just go in and do it all at once. if anything goes wrong with the 44 like boost creep or a spike it will go lean pretty quick. I suppose running 12psi would be okay but just keep an eye on things. as for the turbo squirt some oil in the feed fitting spin the wheels a few times hook everything up make sure it is correct and give it hell, there is no real break-in on a turbo. maybe I shouldn't say give it hell as with new injectors things might be a bit off at first so as always work up to it. enjoy it this is a great combo