Bugger- it can't be a first season can it?! <wail>

[TheFantasticMrsFox]

DPup is about 18 weeks old and lives with 2 entire dogs. We've had her a week and she's been getting on great with DDog2 in particular. The past day though he's become increasingly interested in her back end and has also tried to hump her on numerous occasions (as a virgin he's not so sure where to aim and has variously copped off with her front end, head, side etc :o)
I have seen no blood, no discharge, no licking etc. DPup is completely bemused by his amorous advances, neither encouraging nor rebuffing him.
FWIW DDog1 shows no interest but is a rather prim individual really and has never shown any interest in the ladies so perhaps not a reliable marker :o
She cant be due in already can she?

Meant to add that DDog2 is also sniffing her bedding

No. Really its too soon if you're right with her age. It would be exceptionally early - if you are uncertain, but a white sheet in her bed to spot any discharge.

What breed is she?

If the humper was mine, he'd be thoroughly discouraged and scolded each time he tried. It is not acceptable behaviour in my house!

BUT she can come in from 6 months, so what are your plans to keeping her apart from 2 entire dogs? She is categorically too young to be mated; you'd run a real risk of her dying during pregnancy/labour so you can't afford to get it wrong. And don't underestimate how determined ALL of them will be to get together at a certain point during her season. They will move heaven and earth to do the dirty. Can you send one or other sex somewhere else for a month?

daisy her age is what I've been told, coupled with a date on a vaccination record so accurate to within a couple of weeks.
There's no way she will have puppies, the intention is to have her spayed ASAP. Our vets are happy to spay three months prior to her first season so 3-4 months. However, we are her fourth home in four months, she needs socialising, training and generally catching up on what she's missed in the past 8-ish weeks (she's a Staffie who's come from a drug dealer- you can draw your own conclusions on her early life) Spaying now would be a big issue for all of us (the vets really want her in yesterday as she's at the brink of the three month prior to season cut off)
We are seeing the vet on Monday to discuss whether they would be happy to give a jab to suppress her first season and then spay three months after. What we do depends on their decision but she will categorically not be having puppies... Ever
As for the humper.. We are simply calling him off with an ah ah sort of noise. The fact he's happy to come away also makes me think it's more the novelty than anything else. Not acceptable behaviour here either but a week ago he was Favourite Puppy, a position which despite our best endeavours he has been firmly usurped from- I'm not that keen to hassle him too badly at the moment when the status quo is still not fixed.