For me.....as I cut my pieces for intarsia or segmentation, I place the pieces together in place, just to see how they look and how well the cuttings match. If I find the new piece is a little off in matching or I don't like the way that piece of wood matches, I cut another. After I have all my pieces cut and have the fit that I like, I start shaping and again returning the pieces in the finished position. When I have the finish on all my pieces, except the bottom part, (and my backer board it cut with all the pieces in place on it ), I start on the largest outside pieces and and glue them onto the backer board, resting tightly against the other unglued pieces, that are still in place on the backer board, and let them dry well before I do any more gluing. Once the glue has dried well, I start to glue the pieces that butt up against the glued ones, using the already glued pieces as a barrier. That way I can keep all the pieces matched up well and tightly together. That way I can help to stay away from ending up with a piece that has slid a little out of place from the slippery glue underneath it and making unneeded spaces later along the way.
I love your project, by the way. You did an amazing job. I expect to see more of this kind of work in the future from you. Very exciting project.
Dick
heppnerguy