I think the 20 minute wait is just for the internet cheapies. I really don't know if it's a must or just so that you'll get clearer results.
As for what time of day, you just have to do what works for you. Once you figure out what time of day it shows up in your urine you can test at that time of day for the next cycles.
A good way to know when to start testing is by observing your CM. I know that I get at least 2-3 days of slip-n-slide toilet visits before I ovulate, so I start testing once I get the goo-pants. I suggest the lunchtime testing simply because that works for me. I think the tests give you a big window as to when the test can be successful. And remember: a light line means you're not quite there yet. You really need a line that is at least as dark as the control line to know you'll ovulate sometime in the next day or so.
My HSG went well: speculums are never fun, but otherwise just a weird cramping sensation for about 2 mins and then a tiny bit of spotting over the next day. Tubes look fine, no problems there.