Congratulations on your new career! That you know a great deal of people is indeed wonderful! I think your best bet is to notify them as soon as possible. As soon as you have your business cards, find out if your firm has announcement cards for the purpose and write a nice note and insert your card into it and mail it to all your contacts. If not find a discreet blank announcement (or have one made) card at a stationary or office supply store and do the same. Of course if you see these people on a daily basis be sure to tell them in person and give them your card. You might consider giving a party to announce your new job with perhaps some branded giveaways, some flyers about your firm's listings or the way they do business but at the very least some fun, music, food, drinks, and business cards! (Some mortgage companies will help pay for an informational party where you educate people on the process of buying or selling a home) Good luck!