Baby girl is 2.5 months and I want to start pumping to build up stash. How often/when should I start pumping?

Liz
Baby girl is 2.5 months old and I have not started pumping. Call my lazy or a procrastinator.. But a part of me also doesn't want the reality of going back to work settle 😫 I won't be going back full time and I have sole opportunity to work from home.. But anyway,,
 
How often should I start pumping and when? She is going every 2-3 hours during the day and goes a little longer at night.