I think if they become a more successful country by accepting bitcoin, others will implement too.
I don't think this is true. El Salvador actually took a really bold step in making Bitcoin a legal tender, but tbh, there are actually a few countries that would go along that same line at the moment, not because they do not see the advantages of the Bitcoin network, nor appreciate the way it sets out to change a monotonous traditional fiat system, but just cause they cannot control it, that's basically just the problem governments have with Bitcoin, which is the decentralized nature of the network, they can't print it how they like and they cannot be in the driving seat, so they better just sanction/ban and regulate it.
Should I wait for the success of El Salvador's implemetation of bitcoin before investing?
I don't think you should, the success of the network is not on whatever decision El Salvador has taken, it's a good move from the government of El Salvador by the way, as the decentralized nature of Bitcoin didn't stop them from doing what's right, just do your research about Bitcoin and you'll understand that every time is basically a great time to accumulate it.