eg: When you are hired at a new company, you can say that to your colleagues as a greeting. When you are going to abroad and you arranged a homestay, you can say that to your host family. Therefore, when you are a new face and will be taken care of by someone, you can say that basically just once. That's one of typical Japanese greeting styles.

Thumbs up elanvital!

As yuri said below, direct translation does not work in this case. It basically means "Thank you for your support/cooperation/kindness in advance." But in English you are not supposed to say such a thing in the first place. Maybe something like "I'm looking forward to" (followed by an appropriate verb) would be more suitable. At a new job or to a new business client, you may say "I'm looking forward to be working with you soon." to mean " これからお世話（おせわ）になります。" To your host family, saying "I was looking forward to meeting you." in person would be more like it. The same goes for new in-laws, esp. when you're a newbie in the family. Hope this helps.