Having gone through this, I know this dance is difficult and sometimes feels contradictory. Also don't over analyze every single interaction. If you think something went poorly, make a mental note to do it differently. One bad interaction isn't going to sink the ship.
Boundary setting should be done in general - even in healthy relationships. So doing it before BD is totally fine.
This. This is the lesson I learned before I founde DB, the hard way. Putting too much weight on any single interaction can cause you more pain than necessary, for an interaction that will probably be forgotten about in a day or a week.
Also, I wouldn't put too much pressure on yourself for when the BD happens. In all honesty it is a good thing to assume it will happen, you can prepare yourself mentally for when the dam breaks. Also, because it will give you the opportunity to assert yourself, remain calm, validate, and if you wish state that you also have not been happy with the way that things are going. IMO of course.
