Luckily it's nowhere near the challenge now that it used to be to get. You can easily get it at 180 days. I added it to my reservation at three weeks out, and I've seen quite a few posts from others that were able to add it late and were shocked that there was more availability than the time they were looking at. Don't get me wrong, it does fill up. Just wanted to reassure that at 180 you'll be OK.
In fact, if you'd like to do LeCellier or 'Ohana while you're there, I'd try for those before I went for CRT. LeCellier fills up the instant the phone lines open at 180 days, and 'Ohana doesn't seem to be far behind.