24 x 30= okay for baby blanket??

[AnotherBecca]

I'm having a knitting emergency! I'm *almost* done with a baby blanket and realized I will run out of yarn before it's over. Oh no! I'm knitting with lime green held together with white and although I'll have enough green, I'll run out of white.
Living on an overseas military base makes it difficult to run out to the store and grab some more yarn. The arts & crafts center here has a very limited selection, so I'll keep my fingers crossed that they might have some white in stock tomorrow, but if not, do you think 24 or 25x30 is a sensible size?

Also... running out of the yarn I'm using as a border too (I really must learn to plan better...and finish earlier, the baby shower is on Sunday!) but I did order some. I'm hoping it will be here tomorrow when I check mail, but if it's not, would it be possible to bind off to give the blanket and then hook on and knit the rest of the border after the yarn arrives?

Any and all advice welcome!