You're given a fair number of warnings when you start getting near the end, so it's not like it's going to catch you by surprise. Most of the DLCs are geared towards characters that are level 20-25 anyway, so you still have some time before you need to start thinking about them. For me, I'll play the game until just before I reach the point where there's only one path option left to pursue. The game makes it pretty clear when I've reached that point.

Your character can be confused on what to do and decide to journey into one of the DLCs, of course, there should be a reason for why you get into the area of that DLC.

For my character, he thinks that he has to kill himself if he doesn't have a reason to live, so he just keeps traveling in places where anything could kill him, so that he won't die in a miserable way.

And when he makes it out...he thinks it's a pilgrimage to think about what he did wrong, and the price he paid for it.

In the end, he doesn't want to die...

Mine went into Dead Money for what he thought would be a rest at a relaxing resort, to seek some distance from the problems and choices of the Mojave. A chance to contemplate what he wanted for the future. It didn't work out that way, so he chose to try a relaxing hike through the Zion National Park instead... It was basic curiosity about the satellite and a strange eye that appeared on a billboard which led to Old World Blues. Currently with the Second Battle of Hoover Dam approaching, he wants to understand himself, to be sure that what he is setting in place is for the right reasons. So he chooses to follow a mysterious message which promises answers to his remaining questions...

Even though Benny has the chip, I think he is still stuck halfway through his plan, because he can't get into the Lucky 38. At least that's what Yes-Man says.

So from that standpoint, there really isn't urgency for you to recover the chip, unless your character wants revenge, or wants to use the chip for himself.

We had a thread about this a while back, there was much divergence of opinion as to whether you are railroaded into looking for Benny and the chip.

Since you don't need the chip to finish the game, I don't see the railroading myself.

As for the DLCs, that would depend on your character. Dead Money is very doable at level 1, one of my characters was lured in by the potential treasure.

Another Legion-favoring character went to OWB, HH and LR looking for threats to the Legion, but not DM as she wasn't interested the story of the treasure.

And still another went to DM, OWB and HH looking for adventure, but not very far into LR as he decided Ulysses was a nut-job not worth the trouble of tracking down.

The character I was playing was an agent for the NCR that operated outside the usual chain of command, so obviously I sided with the NCR. Playing the DLCs was largely on a locational basis. I was doing some quests around camp Forlorn Hope when I decided to investigate the source of a strange radio signal that no one seemed to know anything about. A Legion plot, perhaps? Better check it out...

It was simple curiosity that led her to a downed pre-war satellite at an old drive-in theater some time later. But pre-war tech is always valuable, and with the battle looming on the horizon, the NCR can use any edge they can get. Better get out the toolset and start tinkering.

Some time after that, President Kimball was scheduled to make a visit to the Dam in around two months. At this point, Talia was starting to become troubled about the size of her role in consolidating NCR's power in the Mojave, and how she was having some second thoughts. She'd really come to care about the Mojave and its people, something people in her profession are not supposed to do. When she found a signal calling for extra hands in a caravan to Zion, she thought it would be a good opportunity to get some distance on the situation, and hopefully find some clarity.

After Kimball's visit, things were gearing up for the battle. Still, something nagged at her. When she received a message from the man calling himself Ulysses, something drew her to leave her post and check it out. She'd found traces of this man everywhere. The Sierra Madre, Big MT, Zion, it seemed they'd been playing a game of cat and mouse for a long time, and she was not even aware of it. Time to track down this dogged shadow once and for all.