Pretty much all at once.
So, here are the mock up stays:

They have been cut out in their entirety, twice, then version 2 had a partial recut, then several tweaks, so it took 2.75 versions to get a pattern worthy of making up! So, now my fabrics are cut, new, heavy duty zipties purchased, and the next step is to make swatches to decide on the best channel width for these zip ties. The best boning, currently, seems to be hand pounded ash which is 1) expensive and 2) hard to get. SO, since we aren't sure that these stays will work well (we are hopeful, though) and aren't sure that I won't need new ones in a year, anyway (hopeful about that, too!), zip ties are a good, interim choice. Once I decide on a pattern likely to last 5 years, I will get the good stuff and make them completely by hand, channels and all. This pair, machine channels and everything else by hand.

The new, real, pair are cut out. I have heavy duty (thicker, wider, longer) zip ties that need testing, so I will stitch some sample channels, to find out the right channel width, and then I can start sewing my new stays!!!

Yes, they are going to be pink!