The only criteria as being Newbie into Jr. Member is through posting at least once a day until 45 days as the activity increases will increment only every 14 days and you required to have at least 30 activities so that you will become Jr. Member.
Most of the new members in this forum will be stuck on being Jr. Member even you had posted thousands of comments and posts as long as nobody will not give you merits on your comments as most members doesn't care giving merits to some good comments as I do.
You need 45 days in order to bump Jr. Member.