Looks like it! When the gravid spot gets huge and dark you’ll know she’s close!
If you want to save the fry and raise them, make sure to get another small tank. Guppies are known to eat their own babies and so will those neon tetras.
If you wanna save the fry there are two options: move the lady into the isolation tank until she births and then once she’s done move her gently back to the main tank OR if she births in the main tank just gently scoop out any baby fry you see with a net. They’re a little frustrating to catch, as they are small and slippery but with enough patience you’ll get them. They like to hide in plants and pebble substrate so poke around the tank to see if you can find anymore. You gotta be fast though! So they don’t become snacks to the other fish. Most of my ladies give birth at night, so I often wake up and bam! There’s fry in the tank.
Female guppies can get pregnant 8 times per single mating so if your female guppy feels her environment is safe enough, you will probably keep getting fry for a few months. Or! The lady might skip a month or two before rebirthing even if no contact with a man is made. Is a bit of a surprise, haha!