My roos do not get special feed. If my flock is on layer, that is what the roos get. No issues noted, and the roos live a long healthy life. My chicks (and whole flock) stay on starter UNTIL they reach chicken puberty. Any time after that date, I convert the whole flock back to layer.
The bigger issue for you, IMO... Assuming that you only have 2 birds, a bag of feed is going to last at least 45 days. While the feed store employees will tell you that feed is good for up to 6 months, the fact of the matter is: nutrients in your feed immediately start to oxidize after it is milled. The feed looses nutrition. A well published animal feed nutritionist states that feed is at it's best if used within 6 weeks of milling. Given that information, I suggest that you either: freeze half of your feed in an air tight system, and allow that portion to come to room temp before opening it, or find a friend to split a bag of feed with.