Pour It Up is the official 3rd single in the UK also... Don't think its going to do much over here ...
source: 
http://www.radio1.gr/music/forthcoming_uk_singles.htm (reliable)
Rihanna - Pour It Up [29th Apr]
Ideally this should have happened...
Diamonds   - September
Right Now  -  December (performed at XF final) - It charted at #35 the same week.
Stay         -   March (performed at Brit awards & Grammys) 
Pour It Up -   Sent to urban radio in May
Nobody's Business - Music video release May,  Single released June
What Now -  [5th WW single] music video in September released in September
Pour It Up  - Sent to all radio formats [ Official 5th Single in U.S]  Music video in August 
released in Septemebr.
Lov7 Song/What Now - [6th & 7th U.S single ] (Dual release) released in December.
Singles: U.S
Diamonds
Right Now
Stay
Nobody's Business
Pour It Up
Lov7 Song
What Now
Singles: U.K
Diamonds
Right Now
Stay
Nobody's Business
What Now
I think it will go like this though
Pour It Up - 3rd    
Nobody's Business -4th
What Now - 5th 
if she was going to release Right Now she would have released it after Diamonds so and it would've been on her DWT  setlist, so I think its high unlikely Right Now will get released.
next album should be summer 2015.