I've done the solo run a number of times from central Vermont. That was about 1500 miles, so I'm guessing that you must live fairly close to the south wester corner of Connecticut. It's about 900 miles from Mid-Vermont to my current location in central North Carolina, from there to the front gate of WDW is exactly 600 miles. From here I drive straight though. However when I came down here from Vermont I took at least two days, but usually three. I was usually not in a hurry so instead for driving to the point of exhaustion I would drive from home to Fredericksburg getting past the heaviest traffic around Baltimore and DC by bypassing all of it to the west of them. I don't remember the Rte #, it was either I-81 or I-83 or it might have been both, then I'd cut back across to Fredericksburg via 64 &. 17. It's a little further but I'd skip all the heavy traffic and the next day to Walterboro, S. Carolina and then it was a casual drive into Kissimmee.
If two days I would try to get to Richmond, VA and drive through to there, I could never understand those the just drove straight through. Even when was young, I knew I would have been so exhausted that I would not enjoy the expensive day a WDW. Your first day would be about 300 miles less so two days is probably the more doable. I love road trips but my daughters advise me to no longer do that.