Welcome to the obsession Sam.
If you did an extract brew (which I'm going to assume you have), not taking an OG isn't a big deal. You said you boiled off more than expected, so your OG will actually be higher than the recipes (same amount of fermentables, less volume).
You pretty much got it right on. Wait until day 12-14 and take a reading. Then wait another 2 days and take reading number 2. Fermentation should be done by that point unless something odd happens, but it's good to get into the habit of taking 2 readings.