Re: To early for even split? And never done it before :)
I would feed the hive before the split and while the queen is uncapped rather than after.
I have had packages supercede sucessfully when it never hit 50 using the drones that came in the packages (my asumption).
Still, you would be farther ahead to pump up the hives in preparation for the split than splitting early. If they are getting going too fast for the year all by themselves adding a body and frames under the existing is safer than above if the weather changes, in the end weather tends to work out to nearer average than stay at extremes.
4 yrs, 2 singles, 7 nucs, T lite; godfather to brother's 3.