Ugh so fucking long unfortunately. I kind of doubt squishy biological humans will ever make it to another star system, we are so much closer to immortal machine minds that can make the trip much more conveniently than we are to interstellar travel.
Yeah humans being built on the spot is the best shot for us existing in other systems. Maybe if we have a reallllly pro-biological human ideology by that point it'll be something like an automated probe arriving in the system, building an industrial base, and then birthing and raising a new generation of biological humans to inhabit the system.
I'm in the middle of reading A City of Mars, by Kelly and Zach Weinersmith, who goes over their take on the feasibility of long term habitation off world. Short answer is, it's going to be a long time. There are a lot of questions, physically, biologically, legally, logistically, unanswered. At best, it's going to be like building a cathedral. It's a project for multiple generations.
I also like watching Issac Arthur's videos on YT, and fantasize about the future. He gives a more positive spin on stuff like that.
Yeah thinking about the giant challenges of building a settlement on Mars really puts in perspective the much much much harder problem of sending people to another star system.