We can usually prepare and file a design patent application in about 2 weeks

"Patent Pending" occurs when the US Patent Office receives your paperwork for processing. So I guess it depends how fast you can get your ideas typed in the proper format and include all mechanical drawings in the format the USPTO will accept for review; and hopefully approval. This is important: It doesn't mean you have a patent! It means exactly what it implies: The "patent is pending". Protection for your idea(s) is practically nil. I've spoken to several people who get so very excited at "patent pending", when what really counts is patent approval. Only until you have approval (your patent is "issued "by the USPTO) do you have the full force of protection under patent law.
By the book, it takes 18-24 months (sometimes more) to get your patent approved, unless you pay a $1000 "expedite fee". It's well worth it. I paid that fee and got my patent approved in about a year. Now, your patent application may be kicked back for a number of reasons, as mine was. But TtP addressed all the Patent Examiner's concerns, resubmitted it, and it got approved the second time around. Bear in mind that there are fees you must pay to resubmit for a rebuttal. When your patent is finally approved, you'll be happy to pay the $845 "issue fee". You should discuss all possible fees with whoever is handling your patent request.