If there is air in the injector line when the truck is parked, and you wait 6 months, there's still going to be air in the line when you come back.
Once you get it started, the air should dissipate out of the lines by itself.
1990 D-250 Regular Cab: Tweaked injection pump, built transmission, a cataclysmic charlie foxtrot of electronics, the most intense street-ran water injection system in the country, and some more unique stuff.
Should... I have had air stay in the fuel system after hours of running the engine at idle. Thinking it would kick it out thru the return lines. The only way I got it out so the truck would run and drive decent was to loosen the injector nuts an watch the fuel until no bubbles were visible.