Anxious Attachment
A realistic timeline, and what tends to affect how long this takes.
There's no universal number, and I'd be skeptical of anyone who gives you one without knowing your situation. That said, most clients who show up weekly and stay consistent notice meaningful shifts within three to six months, and keep going deeper well beyond that if they choose to.
Attachment patterns were built slowly and tend to shift slowly, even when things are going well. If you're looking for something that resolves in a handful of sessions, this specific approach is probably not the fastest path. If you're looking to change the pattern rather than manage it, the timeline above is a realistic one.