Fair enough.

AFAIK, the direct buses from Kyoto to Itami don't run late in the evening. In this situation, I would suggest that you check out of your hotel in Kyoto in the morning and leave your bags with the concierge until the evening (or drop them at a locker at Kyoto station if you prefer). Spend the day in Kyoto - or make a trip to Nara or whatever - but don't plan on goin n to Itami until after dinner. After dinner, I would take the JR Kyoto Line train to Shin-Osaka and get a cab from there to Itami. (If you have a JR pass or you don't mind paying the Shinkansen fare, you could ride the Shinkansen to Shin-Osaka - but the ordinary train is just a 30 minute ride).

Plan for a boring morning at Itami. I think one or two cafes will be open landside from 6am. Perhaps one very institutional eatery airside (Sky Patio). And - depending on your loyalty program status and/or class of travel - you may have access to a domestic airline lounge, which is nothing special:
http://osaka-airport.co.jp/map/pdf/map.pdf