I let my babies decide re swapping sides. I started out feeding on both sides, but within the first few weeks they settled in to one side each feed.
That's exactly the same as I've done for all three of my babies. My little one generally just takes one side, but if she starts fussing I generally know that she wants to swap sides. I usually means I've accidentally put her on the side that her brother or sister have already drained, lol.