It takes a leap of faith but learning grammar almost exclusively through example sentences is actually really efficient.
Krashen, Khatzumoto, Matt vs. Japan, and Antimoon are all worth reading if you want to go down this rabbit hole.
How you absorb the grammar of a language is a separate question from when you should do conversations though.
Some folks advocate conversation day one, but most pro-input folks do recommend waiting until you have a sense of how things work and can make fewer mistakes.
EDIT: One of the best articles explaining this anti-rule view: http://www.antimoon.com/how/input-gramrules.htm