There could be a couple of things going on that might stop you from entering your score.
First, if it's not 7pm yet, scoring hasn't opened yet. This is especially important on Day 1. You will have no options for scoring on Day 1 before 7pm local time.
Second, if it's after 7pm local time and the site is telling you scoring opens at 7pm, check your time zone setting in your My Profile tab. It should be set to the time zone you are in. If you are traveling, make sure you've adjusted it appropriately, and don't forget to click "SAVE" when you're done.
If neither of these things are the case, please click here to contact customer support and they will get things straightened out for you.