Bitcoin doesn't guarantee that all ledgers become updated at the same time, bitcoin blockchain provides you with consistent ledger following:
- Proof-of-work to cut new block with set of transactions
- Longest chain rule
Above guaranties you that if there no more than 51% of the network controlled by one group you will eventually see consistent ledger, e.g. given your ledger at block sequence number 1001 means all nodes in the network will see identical chain of blocks until 1001.
To your question bitcoins use random overlay network to distribute new blocks (pretty similar to gossip algorithm).