Technically, being "engaged" means you are planning a wedding and getting married as soon as you can get that done. Nowadays because young people don't learn real etiquette and protocol, a lot believe it means you have decided this is the partner for you, whenever you get around to getting married.
Most people think of wedding planning (and later, having babies) as a group participation sport. Be careful NOT to share any details of your wedding- especially with co-workers, who aren't automatically invited to a wedding. Be very very careful not to mix your personal life with your professional life. If you invite some co-workers but not all, you will create problems for your employment. Be professional, and don't talk about it, and if they pry, tell them you agreed with your fiance(e) that you would keep it between you. Then change the subject.
the first question will naturally be the date, because that is the first thing to be determined, after the location. Speak to the clergy or other authority where you wish to be married, and tack down the date, so you get what you want. Those dates go faster than you think. Keep that a secret too.
DO NOT share the details with family, and realize that whomever pays for the wedding has the right to choose what they're paying for. That means that taking money from your parents may mean people on your guest list who are their friends and not yours, and flowers a different kind than you may want. God bless the child that has his own...so keep it secret, pay for as much as you can yourself, and when someone tells you what to do, just say, "thank you so much for the suggestion- we'll consider it". and then don't say anything more.
This is YOUR wedding, and your only wedding. Get the one you want, keep it between the two of you, and remember what it's about.