OBJ may be in around the end of your trip. It frequently starts running by mid-May, but it is early and there will be snow on the banks and perhaps on the road up. This makes it more likely that you would need to hike the run, which is a steep 1-mile uphill walk with your boat. Just watch the weather for the next couple weeks. If it stays unsettled and cool, Oh-Be won't go, if it goes the other way -- warm and consistently sunny -- you'll have a shot.
If you don't already have Whitewater of the SOuthern Rockies, you need to make that purchase (in addition to a good CO atlas or the gazeteer) so that you know how far it is to drive between runs, where the put ins are, and what you'd be getting into. Confluence Kayaks in denver can give you some beta, as can other shops sprinkled around the state.
You should be able to catch the following IV-V runs: gore, piedra, upper animas, escalante, embudo (NM) (solid V, V+ at high), upper taos box (NM, scary sieves), south fork rio grande, gilman gorge (later), barrel springs, crystal river narrows (meatgrinder if you're good and brave), possibly others. Frontrange stuff will take a while yet, but clear creek will be in within a couple weeks.