Is your tri swim in open water or a pool? I kind of skimmed through and didn't see if that was mentioned or not.

If it's in OW, try to get out to do an open water swim. OW swimming is totally different and even though I had gone out several times before my first tri, I was not prepared. It's not worse or even scary (at least for me) but it was definitely out of my "normal".

Other than that, I think you're on the right path. You've got the bike part down and I think you can do the run with relatively little work.

Do you know what tri you're going to do?