First time I installed Gentoo- Spent a week or so and screwed it up. lol
First time I successfully installed it- about a day and a half for the base, same for xfree86 and kde, so about 3 days for a full, bloatware gui Gentoo install. And that was my third or fourth try.....
Since then, installing Gentoo has gotten a lot easier but it is still pretty easy to screw it up, and compiling stuff can take a long time, depending on hardware.
Last time I installed Gentoo it was fairly quick- started in the evening, done in the morning.
But I have had LOTS of practice.
Gentoo is a great distro in a lot of ways, amigo, and well worth the effort if you really want an optimized system. But it still ain't easy.