When building a plan along a timeline, it really doesn’t matter where you start. Decide which way your timeline is going to run, maybe left to right or top to bottom. Choose a card that represents an important topic for you and place it in front of you. Then, if for example your plan is going to run from right to left, start placing things you want to happen before that topic to the left, and those that happen after to the right. Remember nothing is fixed at this time and you can move the cards around until you are happy with the final plan.
Often a lot of things need to happen at the same time, so you plan may have columns crossing the long rows, or even a number of rows running side by side.