Get book market

From my understanding, the ontick() method is called on each new price in the chart in which an EA has been loaded.

So any print in that method, will be executed at each new tick.

However I need to figure out how to get all the prices in the book, without waiting for the price change of the exchange rate on which the expert was loaded.
Here:  you have a list of all function and you can search (Ctrl+f) for book to find the functions that are dealing with the book market like:
Documentation on MQL5: List of MQL5 Functions
Documentation on MQL5: List of MQL5 Functions
List of MQL5 Functions - MQL5 Reference - Reference on algorithmic/automated trading language for MetaTrader 5

You can print messages already on Init – and print out all historical prices or any other information. You can also use OnTimer – and print data on every second or millisecond.