Brake fluid is cheap; go ahead now with fluid change, swap out MC later. Only need to bleed inside calipers after MC change--just to make sure no air got in the lines--not the "wheels off" bleed required for a full fluid change out.....
ps--sounds like the right part number, did you confirm with the thread on this forum? Just make sure the MC shown has the ABS sensor [white plastic plug-in] on the side of the MC.
2003 Alpine 40' MDTS
New Braunfels, Texas