No, you need to BD before that, if you wait until then it will be to late. You may want to use OPKs with this, OPKs will tell you you are about to O, BBT tells you, that you have.
You temp will raise .2 or more after you have O'ed. That is what the 3 or more is about. When your temps have been up for 3 or more days, that confirms O. You pre O temps will be lower then your post O temps for the most part. If you google, BBT charts you can find some great examples and galleries.
Good luck, hope you catch that eggie.