OK, I understand now. I haven't heard of a Kobo going from off to standby without it being turned on first. I don't know what to suggest.
Standby should use more power than off. But, starting up from off should use a lot of power. It is a trade-off between how long it is not going to be used. Personally, I have standby set to 15 minutes and off to never. I don't think there has been a day since I got my Kobo that I haven't used it. The quick wake-up is great for just grabbing few minutes reading during the day.