Is Costco worth it for a two person household?

So my girlfriend and I moved in together recently and we're trying to work out our grocery budget, we probably spend about 500/month on groceries but are trying to get that down. We meal prep and freeze a lot of stuff, we both go through quite a lot of perishables (eggs, butter, bacon, that sort of thing)

I am the sort of person to stand in the aisle at the grocery store and deliberate price by weight and quality for about 30 minutes before making a purchase, so I have been strongly considering grabbing a membership. We also have 4 pets between us and I've heard Costco pet food is insanely cheap and really good for the price. Is it really worth it, or am I better off just shopping the weekly ads at my local H-E-B?

Also, there is a student discount thing for a new membership where I would receive a 30 dollar gift card for signing up, that does sweeten the deal a bit but does anyone know how long it typically takes to get it?