I find it depends on the weather. Mine always bolts as soon as temperatures go up in spring. Some years that is as early as February, but it can go on into March and even April.
The bolting process can happen very fast, so I would plan for whatever you want in that container. If the kale is still going, don’t feel bad about pulling it up. You can bet if you delay things, it will bolt and then you will be behind with the summer crop you wanted.
I play the same Mexican stand off game with chard and overwintered oriental veg as well. The greenhouse oriental veg has already blinked and lost, but the plot stuff is standing firm … so far.