For now, make a dwg. and in detail describe how it works. Sign and date this paper. Put it in an envelope, seal it, and address it to yourself. Take this to the post office and have the postal date seal stamped on the envelope seal. Then pay the postage, mail it to yourself. Do not open this envelope, you may need to present this to your patent attorney, if you proceed with a patent.
Mailing somehting to your self is not a sufficient information when it comes to the courts. Go to www.inventorfraud.com you will find good information. Do not fall for the T.V advertisings. That promise to take your idea and give a patent # and many dollars.
Investigate the patent attorney very thoroughly. Don't tell anybody about your idea before Documenting it as detailed as possible in a hard bound notebook not a loose leaf.
Edward, "Mailing somehting to your self is not a sufficient information when it comes to the courts." This holds up very well in the courts, post search, and file date, however, you still must proceed with search, and any pending material. As you noted the selection of a qualified attorney is important, best if you can find one that is expert in the area of your invention. I have four inventions to my credit, three are in the construction market, one in tooling. The first one was an education all by itself. One of the products went to UL for testing, and that is a project by itself.