LLC in Maryland
If you are making a lot of changes to your existing company, including the type of entity and the ownership, I would recommend that you start afresh and form a new LLC and then dissolve your old corporation. There is one caveat to this route, you may not be able to use the same name of your existing company in forming a new one, but usually adding one word like "Enterprises" or "Group" or "Venture" to the name of the new company would get you out of that predicament.
Regular processing by the Maryland authorities takes about 6-8 weeks, but you can expedited to take as little as 5 business days for an additional fee. To that time you have to add the mailing time and the processing time for whomever you entrust to handle the paperwork for you.