Even if you can’t make the time
Even if you can’t make it in time, you at least need to go the distance. Triathlons and other long-distance events aren’t so much about the time. That’s only really true if you’re an elite athlete, or if you’re going for a PB. For everyone else, simply going the distance is the real aim.
Even if it takes you much longer than expected, at the very least, go the distance. You’ll be that much closer to getting your wanted time next time.