Because of the unusual nature of the rapid cloning project (there are too many uncertain variables in replicant biology that Skynet needs to analyze personally), very large tissue samples must be returned to 2029. This means that one single T-800 must go to the alternate 2019 Los Angeles and terminate all 6 replicants in order to collect the appropriate body parts. Standard procedure must be followed: arrive naked in destination era, acquire clothing, purchase weaponry, blend in as inconspicuously as possible (yeah, right), and track down the targets.
The T-800 arrives in the outer reaches of LA just at the moment where we first meet Rick Deckard reading the paper early in the movie. He is still kilometres away from any one of the replicants. By now, 4 of the replicants are not only wary of the law, but of anyone resembling a bounty hunter, or anyone equally suspicious.
The T-800 has sufficient data regarding the LA of this particular era and timeline, thanks to Skynet's mysterious ability to read databases of select parallel universes (just go with it

The replicants know nothing just yet. The question is: how quickly do they learn? Will they be prepared?