Tom's hint and link are just the right ones for you to start. Don't think too much about ifs and whens, even before starting. To go through Terry's course you'll need just goggles and trunks... and a pool. Nothing else. A friend having a look at or taking a video one and then will be helpful too.
If you read the first book, UEF, of the course while working through the workbook and videos, surely your whole thinking about swimming and your stroke will change.
Enjoy every minute in and out the water!