We don't know how Rita's story started, but like most slaves in Gilead, she would have been forced into a vast complex of cages--perhaps setup in a repurposed cattle barn or warehouse, where groups of women were penned in with metal fencing.
They'd be forced to share a pair of buckets for waste, while they stood covered in their own filth, disturbed by the sound of distant screams and rifle fire. The passage of time would've been slow, drawing out every second of their torment.
Guards might come, drag some women out, beat them, and push them back in. Then, at some indeterminate time, they'd blow a whistle and everyone would line up. Someone would yell over a loudspeaker, announcing their fates, and one by one, the guards would grab them and push them onto a bus.
By then, Rita might've figured out that only fertile women were allowed to live full lives. If she knew her fertility status she'd know that she was looking at either a quick death in the colonies or a slow death as a servant. Either way, she'd have to work until she couldn't work any longer.