1. Tell everyone you know that you're in the business.
2. Send out letters announcing your new career to your sphere of influence
3. Sit in every open house you can find.
4. Ask experienced agents to give you buyer leads they might be too busy to handle.
5. Join a service club (such as Rotary)
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!
Sphere of influence is a great way. I think it is all about balance. Hit hard in the beginning with open houses, farming in some form and internet. Read as much as you can on a variety of sites to educate yourself. I think it is all about balance, a little of it all and see where you find the most success. Build on what seems to work for you but don't stop the other avenues, just drive your focus on what works for you!
Best of Luck.
Your sphere of influence will probably be your number one income generator. As far as what to expect, aim high, but don't be discouraged if it takes a little while to get going.
Best of luck to you!