easy. you just sit there and do a thousand tactics. an hour or so every day for 3 months.
1400 Rated Chess.com player wants to get to 1800 in 3 months w/ PLAN OF ACTION

easy. you just sit there and do a thousand tactics. an hour or so every day for 3 months.
For me, that seemed to work in getting my tactics strength up, but after I passed 2200 I got tired easier, I have to cut down. Now I use it as my warm up for real training, 2600 tactics are really hard.
Tactics are a nice bonus, but they should not be your only training.

People who set these kinds of goals often give up when they realize they can't accomplish it. It's a very superficial approach to playing chess (or doing anything really). Chess is cruel, so you only keep playing if you actually like the game, and not just after some number points...
Ok, 400 points in 3 months is a bit much. But I seem to meet my goals, similar goals I just give myself 7-8 months instead.
And I like the game a lot! Even more vs hard players, and my losses are more valuable than my wins.

Do you play real tournaments? You know, otb ones.
Yeah, every month and a half or so. I have gained about 600 points this year.
http://www.uschess.org/msa/MbrDtlMain.php?14194968
Do you?

Eight hours a day huh?My guess is that in 3 months you will burned out on chess after that.Chess isnt like track.The brain needs to rest after a grueling long study time.Cut back your hours.Concentrate on learning and not on ratings.Have fun in chess and life.
I wonder whatever happened to our dear OP, he seemed so determined! At any rate, lots of fantastic advice here for someone who is at about the same skill level (I'm about 1375-1400 or so the chess app on my tablet informs me) and who also wants to step it up a few hundred points... however long it takes.