It'll be about four months at your current rate; in the meantime, try to improve the quality of your posts. There's no reason to want high activity except for signature campaigns, and they won't pay you unless you improve your posts considerably. Try to write out longer and more thoughtful responses, use proper spelling, grammar, and sentence structure, and avoid posting things like "+1", "I agree", and this one you wrote yesterday:
I don't think he's doing it for a signature campaign. He probably thought he could spam his way to senior member in a day or two and then sell the account.
140 shity one-line posts in a few days is not going to make a Full Member go Senior? I wonder why he isnt banned yet.