Yep - your options trickle in over a vesting period.
Typically there’s also a ‘Cliff’ at the start - a period during which no options are available to you.
addendum: the ‘standard’ Silicon Valley stock option deal is: 4 year vest, 1 year cliff.
Eg: first 12 months, no options
Day 1 of 13th month - 25% of your options are available to you
Then the rest of the 3 years vest at a regular pace with the remaining 75% of your options dropping on a monthly cadence
The exception being Amazon who basically give you nothing for 2 years and then ramp up significantly.