Mike, congratulations on finding ''the'' boat. And I agree with Jeff''s general description, she''s a moderate choice in many respects and overall a decent cruising choice. Read some of the on-line reviews of the boat, as well. It will give you things to think about during the survey and fitout.
I think your broker is giving you good advice (about departure timing). As just one example, good friends left RI in a sistership to WHOOSH (33'' waterline, powerful engine) and worked hard to get south. They did hit the Annapolis Show, as do many boats going South, but it was slow going (fronts start showing up regularly in September, just when you''re doing some longer runs in a new to you boat) and they didn''t enjoy it much. By the time they made it to the FL border, they were disgusted and had Racoon Tans: cheeks and chin tanned, eye sockets and everything else Albino White. The problem is two fold: first, you''re doing this to have fun, which means stopping to smell the roses regularly. OTOH a good day of weather will motivate you to move the boat, while a bad day will make going ashore a hassle. And then there''s the autumnal weather and sky: each day is shorter (meaning less time to move the boat, forcing you into the ends of the day when its colder), you would want very good cockpit protection to be comfy. Frontal systems increase in number & then severity, which means more hard wind, and cold/wet going. Going offshore is harder going South than North, and with a new boat you''d be more likely to stay inside, anyway. None of this says it can''t be done, and in mild falls-early winters, boats don''t have too hard a time...but they don''t see a lot either, as they work hard to stay ahead of the frost belt. I hope NONE of this discourages you from making the trip, it''s a joy and a special chance to reconnect with America''s roots and what makes her (still) the wonderful country she is. But better you think about the circumstances going in...
Finally, there''s the issue Jeff mentioned re: prepping the boat. You can''t really expect to do more than insure the basic systems are in place, key spares are aboard, you have the right tools and consumables, the navigation is locked up tight, and everything works (it won''t) with time to adjust/repair/replace/amend. This takes time, which is time away from becoming familiar with the boat, thinking about how you might want to modify things, etc. You might consider asking the owner for a day on the water right now, as the sales process unfolds, to see what you think about the boat''s current condition and exercise every piece of gear. Explain this is in her/his interest as it might speed up the sale. If it seems to you that there''s a significant gap between time needed and time remaining, it will free you up to move methodically thru the sale (e.g. when negotiating niggly survey issues).
Folks we spent time with who''d left your neck of the woods, come south in their T33 (same hull/underbody/engine) and were again headed north mentioned to us that it was a slow boat when motoring into a chop or without a sail up. 40NM-day is not a bad estimate and that would be a full workday at 5 kts...not counting bridges, adverse tidal currents in the Carolinas, etc.
Good luck and I hope it comes together for you.