I'm not FTM, but just from having read the threads here, cutting your hair short, getting a binder seem to help them through the early periods, I've also heard there can be health risks to binding though so that's something to research properly... Even if you can't get men's clothes for some reason you can keep it to simple jeans, t shirt, sneakers.
I'm sure a friendly FTM member will have more to say though.
I'm sort of in the same boat at the moment, I'm starting the process to get hormones, but sort of doing the opposite of that advice has helped me, started to grow my hair out, I fit in frills where I can get away with it, and since I've already got the T figured I'd use it to my advantage and work out my hips and thighs to make them look more feminine.