In my experience, milestones tend to get shattered the first time. By that I mean, I had a lot of rounds where I shot 80 on the number. I'd start thinking about it, tell myself I could just bogey the last three holes and still shoot 79, and then I'd go bogey, bogey, double. But when I finally broke 80, I shot like a 76 or something. I got into the same position and parred out. Same for breaking 70. I'd been around there a few times, but when I finally broke 70, I shot 66. Granted, it was from the white tees (corporate outing) at a par 70 that wasn't super tough, but I'm not giving it back.
In college, our team advisor (we were a D2 club team, and he more or less organized it) had two young kids. They were playing behind us one day at Victoria Club in Riverside, and the younger one had never broken 50 for nine holes. The day finally arrived, and the poor kid made 7 on the ninth hole to shoot 50 on the number and was just bawling. Everyone who has aimed for a milestone has a story like that. The kid ended up OK, and played fairly big time college golf.