Hello Antonin,
The forecast and the wave height projections appear below. I like Jupiter but have also been riding in waves for almost 12 years on kites. I can recall folks having difficulties in the break there if they weren't used to it. NE is close to onshore there, toss in a breaker line and getting out can be difficult at times. These aren't very big conditions for Juno/Jupiter either as it can get quite a bit larger.
For a first time in waves, you might do better a bit further south IF waves develop as forecast. This may not happen this time. With each inlet you pass heading south the wave height drops. Delray Beach might be better for you although even there getting out can be challenging at times with near onshore winds. For a first time out you would do a lot better with side or side onshore winds. These aren't in the forecast in the area unfortunately for this weekend. The kite beach is south of Atlantic Ave, off the guarded beach about 150 yards south of Casurina Road. We need to stay away from the guarded beach there. There is about a mile and a half of private beach south of there with fewer issues. If the winds are lighter or later in arriving the waves could well be less of a factor.
Regarding Juno, I would ignore the other two spots particularly the inlet as the beach can be very narrow, there can also be surfers and tidal currents. Not a good spot for a first venture. You might be fine in Juno but the place to go is kitebeach, about a mile north of the Juno fishing pier and well south of the Inlet. The waves may not be much of an issue depending on how conditions develop. I would be sure to check the forecast again tonight and even in the morning if you are driving over Saturday. There is a nice livecam of Jupiter inlet and Boca Raton further south which shows conditions similar to Delray at:
http://fksa.org/showthread.php?t=6734
Have a good trip!
Tonight...East northeast winds 12 to 17 knots. Seas 2 to 4 feet. Dominant period 4 seconds. Intracoastal waters a moderate chop.
Saturday...East northeast winds 15 to 20 knots. Seas 3 to 5 feet. Dominant period 5 seconds. Intracoastal waters choppy in exposed areas.
Saturday Night And Sunday...East winds 15 to 20 knots. Seas 4 to 6 feet. Intracoastal waters choppy in exposed areas. Isolated showers.
Sunday Night...East southeast winds 13 to 18 knots. Seas 4 to 6 feet. Intracoastal waters choppy in exposed areas. Isolated showers and thunderstorms.