If you just got engaged, Congratulations!! Of course you are going to want to tell everyone about your engagement, including your parents,best friends, friends, people lining up behind you at the supermarket. That said, what about the people you work with?
The first person you should tell is your boss. Not your closest coworkers. Your boss. Yes, this can be scary because you worry that your boss will think you will be in la-la-land up until your wedding now. To prevent this, prior to telling your boss, have a plan in place. Explain how you will be dealing with your professional obligations before and after the wedding. Assure your boss that you will be the same hardworking employee the day before your engagement.
Be considerate about when to take time off for vendor appointments and your wedding. Some days and months are just worse than others for certain professions. If you are an accountant, try not to take time off during tax return season. Get it?
If you are worried that your boss might think you will be in la-la-land during your entire engagement, just don't do stuff that will make him/her think that. Don't change your work habits. If you normally take work home and work late, try to continue to do that. You might not be able to all the time but if you work hard, your boss might cut you some slack.
After you set your wedding date, tell your boss first. You don't have to necessarily change it if that time or date doesn't work with the work schedule, but it will give your boss enough time to plan and make any changes as necessary for the team.
Remember, although you are getting married, you will still have to be a team player. Especially, if you want your team to attend your wedding, be happy for you, and pitch in at work when you are on your honeymoon.