Terraforming would seem a bit unnecessary if you can send a crewed ship there. Manned interstellar travel, unless we're wrong about the whole speed of light thing, is going to take decades at least to reach the very nearest stars (I'd imagine that it is more likely we'd go to those stars first, and only reach Trappist when people from those stars later launch their own ships, until eventually the outer edge of settled space reaches 40ly).

That implies that, if you can send some colony ship to another star, you necessarily have the technology to build a space habitat that can sustain large numbers of humans in sufficient comfort to run a small civilization and all relevant industry, self-sufficiently using only the materials available in space from asteroids and such as inputs. You have this tech first, because the colony ship is itself just one or more of these habitats, on top of some massive propulsion system.

As such, why even bother with terraforming planets? That's a process that may potentially take millennia to truly finish, longer than it took your ship to even get there with some of the possible propulsion options, will only be viable on a fraction of worlds, and will still get you a place that probably does not have an earth like day or gravity or any number of other differences. You would then be back in the bottom of a gravity well, which requires a ton of energy expenditure to get back into space again. Why not instead, find some asteroids and comets in your target system, there's probably going to be some around somewhere if our solar system is any indication, and build more of those habitats as needed.