I think you will find a variety of answers from different GCs. In our case, our site finished hardwood floors where installed, the cabinetry went in and then the trim carpenters arrived. Things that happened after the trim guys left included painting, tile, countertops and the trades (electrical, plumbers, hvac) coming back to finish fixture installation.

Typically, but not set in stone, after the drywall is finished,(mudded), and textured,(if it's going to be), but before paint/stain. Common practice is for the finish carpenter(s) to hang all the doors, case them out, run baseboards, hang cabinets, etc after the drywall has been finished. Then all is painted/stained. I have seen homes where they prefered to paint the walls and pre-paint or stain the trims installing them after the fact with touch up. Cabinetry is dependent on whether they are pre-finished or finished onsite. Different strokes for different folks!

Yeah, you would think "trim" would be the last thing put in wouldn't you? Kind of like putting the ribbon on a package? However, nowadays it often is installed much earlier than you would think.

If your interior trim will be painted, it is likely to be installed before the walls are painted so that it can all be primed at the same time using a sprayer. The trim will then be painted - usually with a fairly glossy paint and, when that is dry the trim will be masked off while the walls are spray painted. Once the paint is dry, the painters will go back and touch up any places where wall paint got on the trim. It's quick and easy but means that your cabinets, flooring and all sorts of other work that you wouldn't want to get paint on will be done afterwards.

With stain quality trimwork, I think they usually (but not always) paint the walls before installing the trim so as to avoid the risk of getting paint on the trim. However it is also possible to stain the trim and put a polyurethane coat over it so that any paint that gets past the tape masking can be cleaned off relatively easy. So, once again your trim might be put in well before flooring, cabinetry, etc.

While quick and easy there are, in my opinion, several problems with this standard approach.

If you ever decide to remove the trim for any reason (say you decide you want to run some speaker wires behind the trim rather than cutting holes into your walls) the overlapping layers of paint between wall and trim usually means that you'll tear paint away from your walls when you take down the trim. [Been there, done that.]

Also, when baseboard trim is installed before floors, it never quite serves its true purpose of created a finished edge where wall and floor meet.

With tile floors, putting the baseboards in first means that there is always a line of visible grout all around the edge of each room. And, if any cut tiles at the edges are not cut perfectly, you can see the mistakes. Once you notice this in a house, it becomes impossible to overlook. If the baseboards and shoe molding are put in AFTER the tile is laid and grouted, that outside grout line and the cut edges of the outer line of tiles is covered by the trim which rides above the floor... a much cleaner and more professional looking finish IMHO.

With hardwoods, putting the baseboards down first means that you end up with a small gap around the sides...which has to be there to allow for wood expansion in the summer. This gap becomes more noticeable in the winter when the wood contracts. Again, if the floors are installed first, the expansion gap around the edges is covered by the baseboards as it should be.

After looking at homes by a number of builders and realizing that standard practice for all of them was to put the trim in early, we had it put into our contract that floors are to be installed and finished BEFORE the baseboards are put in. Its a little thing...probably something most people never consciously notice...but I think at a subconscious level, when done right, it is one of those things you can't quite put your finger on that makes the occasional house seem just so much nicer than the average.

Bevangel -- shoe moulding (quarter round) covers a lot of those gaps either way.

I've never seen a house that was walked away from leaving the expansion/contraction joint open. It's either taken care of by shoe moulding as Heimert mentioned, or the flooring is layed down before any trims which makes it easier to deal with door jambs as well. The risk on pre-finished flooring is it getting scratches even when covered, but reputable builders make sure that it is covered well/protected during the process.