Pregnant cat first litter, is labor soon

I have a 4 year old pregnant cat, its her first litter I got her at a year old and was told by the old owner she can't get pregnant, I never actually seen her go into heat until about 2 months ago so I completely believed this person until now, she got out during a birthday party (strictly indoor cat) went missing 4 days, I had flyers, post on Craigslist, Facebook etc etc then one day someone said they found her under their porch and brought her home, a month lalater noticed her gaining a little weight, slowly it got more, now she's not as huge as some pictures I've seen of pregnant cats but she's still big for her size, well anyway the last 2 days she's been more clingy, meowing more which she never does, licking my hand lick crazy and the kittens look like they're boiling in her belly, also maybe a little licking of her private area, here's what I don't see
I don't see milk, I don't see discharge , she's still eating a lot, her breathing is slightly heavy but she doesn't leave my side only to tongue off the bed or chair but she's always right back up within 5 minutes
I know she's due this week by calculations
She's very restless, she didn't nap at all today or yesterday just a little sleep curled up under my arm last night,
And before its commented I already made arrangements for her to be spayed in August and got a hold of her old owner threw email to tell them they were wrong!!! yes the kittens have homes and spay and neutare agreements
Anyway does anyone know how close we are to her having these babies

It sounds like she's close to delivery. Her clinginess is a sign. She also will want to start nesting. Prepare a nest for her in case. This site has many articles about the care of pregnant moms and kittens, and I suggest you take the time to read them. It will help and relieve your mind some.