I don't know how your DBT group works.....but with ours, people are only allowed to start at the beginning of a section. It's divided into 6 sections

Mindfulness (3 weeks)
Emotional regulation (6-8 weeks)
Mindfulness (3 weeks) (same as the first one)
Distress tolerance (6-8 weeks)
Mindfulness (3 weeks)
Interpersonal Effectiveness (8-10 weeks)

One cannot just start in the middle of the session & they usually want you to start with the mindfulness section, so if for some reason the session didn't start when your T thought it started, you might have missed the start of the session which is the cause for your wait.......I do know how when you are all ready to start something emotionally & intellectually & it doesn't happen, there is a definite let down.

You will get there & it will be more than worth it.....DBT is the first & ONLY therapy that truly makes sense IMO......I love it & can see it works in every area of my life......took me awhile to get into it & understand it.....but our leader is WONDERFUL & holds our hands & teaches it like a class along with a group........it's the best experience I have ever had in therapy.