Rih is touring both Europe & US this year which means 5/6/7 months on tour so she has to release the album before Summer. She won't go on a stadium tour for HOME. There are these rumors of a US tour with Kanye and it sounds legit (they were spotted 2 or 3 times in the studio + did a shoot together + the Clara Lionel foundation tour items bid). A tour with Kanye would be R8 related for sure.
I don't think Dreamworks can force Rih to release R8 months away from HOME, she decides everything about her own album.
As for the sales, the album will sell cause everybody's thirsty for it, doesn't matter when it's release at this point. A lot of pop girls released in February/March (Shakira, Adele, Kylie Minogue, etc).