If you’re buying a wood board, you’re going to want to oil it every 3 – 4 weeks to keep moisture out and prevent warps and cracks.
Most importantly, get the right oil. What you don’t want are oils that will go rancid over time, like olive, canola, or coconut oil.
Instead, I recommend Howard’s Butcher Block Oil. It’s food-grade mineral oil (doesn’t go rancid) stabilized with vitamin E.