@gtg: Time is a very

Time is a very limited resource in my case so I prefer planning to minimize unexpected wastes.
Old-school highway tolls are problematic and a reason of traffic congestion during peak season, unfortunately new system will be online two months after the HiveFest.
If you will be driving more in HR, you might consider getting ENC once you enter, it should reduce your highway costs and potentially waiting in queues (separate/faster gates for vehicles with ENC device).
For me ENC not worth the hassle as we will be just driving for two days, and the day that includes Plitvice implies driving mostly off the highways.

from my xp of the old school tolls system is to try to miss the peak hours near bigger cities. I am mostly missing Belgrade and Zagreb could maybe be a problem. My biggest concern on time wasting is the border. Last time i was lucky as it was 5 minutes with 2 cars in front of me, but there were days this year that people were on the border for over 4 hours.
Still not sure when to go. Check in is after 16h, so early morning would make sense, but i like driving at night and not a morning person :)

Well, borders, we don't do that here very often ;-)
I will be driving through five countries but they all are in Schengen.

Consider using Croatia Traffic Info - HAK (Link is for Android) It's really convenient to check the cameras on highways and border crossings, so you can try to figure out one week earlier same day how does it look like at your preferred times.

Thanks for the link.

Well, borders, we don't do that here very often ;-)
I will be driving through five countries but they all are in Schengen.

Thanks for the link.