Outer Wilds is an exploration game about curiosity, roasting marshmallows, and unravelling the mysteries of the cosmos.
Explore an alien world of campfire tunes and celestial wonders that evolve over time. Investigate tales of quantum phenomena and launch probes into the depths of space. The answers are there for those who seek them.
Fasten your hiking boots, check your oxygen and fuel levels, and venture into the unknown.
Rule 1: All spoilers must be spoiler marked, do not post spoilers in titles.
This is an old post so I'm sure you've already found your answer, but to anybody else stumbling upon this I will say that the DLC content, if installed, is fully available to explore while playing the base game. However, if you happen to find it before having completed the full game you're going to miss out on a fantastic emotional moment and you'll never experience it the same way again after.
Play the base game all the way through first, then get the DLC.
You can disable the DLC if you want right?
You can wait install later I guess. It's extremely unlikely you'll stumble across it on accident, but it happens on rare occasions. If you do install it just don't investigate the radio tower on the home planet.
As other said, it's up to you, it blend well with the rest of the base game (tho it have a different ambience and thematic) so you can install both and treat it as a whole, or play the base game first and then DLC. An important note is that some part of the ending of the DLC are not shown if you haven't discovered some part of the base game (can't say more to avoid spoiler), so if you decide to play DLC after the base game do it on the same save, do not start on a fresh one.
At one point you will know what to do to reach the end of the base game, I personaly think it is at that moment that you'll have to choose between completing the DLC or reaching the ending. Until that, focus on discovering the base game.
tldr: both base game -> DLC -> ending or base game -> ending -> DLC are fine, it's up to you.