Where should a miner get the most current block from?
You've asked two different questions and already answered one of them.

Solo miners get blocks from their peers on the network.

Discovering peers is done by a bootstrapping process. Basically, the software comes with a default list of known nodes, and from these nodes the client learns about other nodes. More details are at https://en.bitcoin.it/wiki/Satoshi_Client_Node_Discovery.