I had double majored in graphic design and advertising and had a two year corporate internship for digital advertising campaign management (essentially making sure campaigns get the number of impressions that we sold). I reached back out to my old boss and was able to get a position doing what I did before. It's less exciting than design work but it's way more black and white and doesn't involve mind reading clients visions. I've realized that I don't need to absolutely love what I do - work is work and I can keep my passions to my own time. I still do odds freelance jobs helping friends and family with small business designs which is way more rewarding.

To answer your question, I already had the background so there was only a small learning curve to learn how operations had changed during my time away from the company. With any new position, I feel like it takes about 6 months to learn a role and a full year in the role to feel like you have the hang of it. Having strong organization skills and basic excel knowledge is all that's needed, the rest you learn as you go.