I posted my first post on bitcointalk.org on 8 Feb 2018 and have around 55 posts since. but i am still a newbie when my status will change to Jr member level
You are a jr member now.
Also, as I understand, we can post a whole lot of posts but we can only have as much activity for 2 weeks, and that would be 14.
This is to prevent pone from posting a hundred times in a day and ranks up tomorrow as a member.
It's a pretty well designed rule.