Also, remember that a replicator only has to develop once during this time. Once it forms, it will begin replicating. The first replicator will become two. Each of those two will become two. Each of those four will become two. Each of those eight will become two. Each of those sixteen will become two. And so on.
This exponential growth rate will result in a lot of resultant replicators over a short period of time. If it takes 1 month for a single replicator to replicate (which is a long replication time for a single molecule), after 1 year, 4,096 replicators will be floating around. After 2 years, there will be over 16 million replicators! And we've had several hundred million years for all this to occur.
The evolution of these replicators into what we see today in our genes is a topic for another study.
Successful replicators exhibit three properties: