P.S.
Another way to handle a mis-match between your springtime and Bok Choy's preferences is to save a LOT of seed, even if it might be cross-pollinated.
In fall or spring, broadcast-sow it very thickly and then harvest it at the baby leaf or micro-green stage before it can even think about bolting.
The baby leaves can be used raw in salad, like spinach, or in sandwiches, or as a garnish.