This is only a guess.
Well at your current pace of increase of 200 points (from 1200 where you start) in 5 months, after 10 months (5 to 6 months from now) it's safe to assume you could reach 1600 if you continue to study and practice at the same intensity as you did during the first 4-5 months. Then another 200 every 4-5 months would put you at your next milestone in a couple months shy of a year from now.
1400 is good though for only playing a few months!
Hey!
I have been playing chess for about 4,5 months and have so far roughly gained a 1400 blitz rating. I feel as if I am at a level where it's harder to improve so I'm wondering, how long should it take for me to get to my next milestone, a rating of 1800?