I'm new to cookies, but it seems to me like decorating them takes 2-3 days.

Bake on day 1.
Day 1 or 2 - Flood the base royal icing (if doing 2 layers). Can I do this on the same day that I bake them or will it cause problems with the oil leaching out? I saw a few mentions of this in the forum.
Day 2 or 3 - Add any additional royal icing layers. I'm thinking in terms of stenciling here. Let dry overnight.
Day 3 or 4 - Package.

Is this right?

That is usually my timeline. I like to bake on day 1, decorate on day 2 and 3 depending on design, and package on day 4. I work full time so the only time I get to work on cookies is the evenings after dinner so I have to schedule my time very carefully. If possible I give decorating an extra day just for cushion. It works great for me.

Thanks. I made a batch yesterday to try my hand at cookies. I'm wondering how fresh they'll be over the course of 4 days, but it didn't seem like any other way to decorate them faster.

Royal Icing Cookies stay fresh for a week.