Well, you know the old saying: if you have time to spare... etc.
If you
have to be there for work on a given day, then I would plan to fly at least two or three days before that date, and have another two or three days to spare on the other end too. Especially if flying SE VFR and over all that water (= no alternates. PNR approx. 1:45).
I don't know your experience, capabilities, equipment, or luck, but from what you have posted it sounds like an uncomfortably risky proposition.
Plan 'B': Buy a KLM ticket now just in case (perhaps on a refundable fare), and if the weather is 100% good on the day then you go smashing bugs, else you let someone else do the flying. Then of course the same considerations apply on the return leg.
