Hi, RimRoc,
Personally, I would wait until about 12 weeks or so before doing an activity like this. You don't have much strength or mobility in your leg yet. You will also get exhausted very easily at this early stage.
I'm a sailor, and my 26 ft boat has very high freeboard, which makes it difficult to get in & out of. One has to step up & over the hull to board or disembark. At the 4 week mark, I asked my home PT when it would be appropriate to go sailing again, and she said 12 weeks. At 6 weeks, I started out-patient PT, and my new PT also agreed with that assessment. I actually cheated a bit, and went out on the boat at 10 weeks. By then I had 120 degree ROM, and pretty decent strength. I was 2 weeks away from going back to work. I didn't sail, but just motored the boat around the bay. That meant that I didn't have to go up on the deck to raise & lower the sails. I was able to get in & out of the boat fine, but the whole trip took an exhausting toll on me. I didn't go back out again until about 14 weeks.
If you do decide to go kayaking, I would strongly recommend that you have a companion, either in your kayak (if it is a double seater), or in another kayak, to accompany you. This is just in case you run into trouble. And definitely wear a PFD. If you are ocean kayaking, then I would suggest going out only when conditions are calm.
As to how to get into the kayak: Does the kayak sit level with the dock when it is in the water? Or do you have to step down into it? Stepping down into it might be more difficult, but I would suggest that you have someone available who could steady the boat for you. Go in both feet first in front of you, with both feet down into the boat, then use both arms behind you to steady yourself against the dock. Then slowly turn yourself around, still using your arms on the dock, and sit down.
I hope this helps. Good luck in your recovery, and I hope you heal quickly!
Cheers,
Roger