Not sure I understand you correctly but you can work out when you'll be a certain rank with this table (providing you make a post in each period and enough posts to rank up):
1 X 14 = 14
2 X 14 = 28
3 X 14 = 42 Jnr Member (1.5 month)
4 X 14 = 56
5 X 14 = 70 Member (2.5 month)
6 X 14 = 84
7 X 14 = 98
8 X 14 = 112
9 X 14 = 126 Full Member (4.5 month)
10 X 14 = 140
11 X 14 = 154
12 X 14 = 168
13 X 14 = 182
14 X 14 = 196
15 X 14 = 210
16 X 14 = 224
17 X 14 = 238
18 X 14 = 252 Senior Member (8.5 month)
19 X 14 = 266
20 X 14 = 280
21 X 14 = 294
22 X 14 = 308
23 X 14 = 322
24 X 14 = 336
25 X 14 = 350
26 X 14 = 364
27 X 14 = 378
28 X 14 = 392
29 X 14 = 406
30 X 14 = 420
31 X 14 = 434
32 X 14 = 448
33 X 14 = 462
34 X 14 = 476
35 X 14 = 490 Hero Member (more than a year)
You'll be a Full Member on the 17th of March (again, providing you make the required posts).
if its really like this i will make it in 6months to hero i think