+0
This evening was the scariest evening of my life! It started out/off OK. Tom and I were sitting at home, watching a game show. Then someone started knocking on/at our door.

Do both started out and started off sound right and convey the same idea? If yes, could I replace them with "In the beginning, every thing was OK?"

In addition, what is the slight difference between knocking on and at our door if there really is difference?
+0
No significant differences, and all are OK except that everything is one word.
Comments  
Thanks, Mister.

Got it.