I doubt they have dried significantly, so they may check a little
more. There is likely a good bit more drying to be done. If the
present checking is not too long, up the length of the boards, cover/
wrap the checked areas (rather than paint, lengthwise, along the board
faces). Maintain the painted ends.
I wouldn't cut off the checked ends, yet. Do your cutting when you're
ready to do the future project, when the boards are dry enough for
doing the future project.
Most useful lumber, in a home, is in lengths of 8' or less. Most
lumber is milled in lengths a bit beyond 8', as you did. This extra
length allows for checked ends to be cut off, later, hence fitting the
8' or less in-home use. I've always cut my logs, or had them cut, to
9', so as to have 6" cutoff allowance on each end.