Congratulations It will probably go well since Pumba is still so young.
I would start by introducing them on neutral ground, so Pumba won't feel that she's intruding on his space. We usually take our dogs out for a walk with the new dog, it's a good way for them to bond.
Bulldogs are pretty sensitive, he might feel jealous. My Boeboe was incredibly unhappy when we brought home Bennie. She was about 6 months old and Bennie was 10 weeks. Boeboe was sulking for a week, sometimes even sitting in a corner facing the wall, aww. I felt so bad, but she came around I'm not gonna lie, they're not great friends, they never cuddle but they do play with each other which is very fun to watch.
I think it's easier though to first have the male and get the female second, I personally think females are more difficult in general.
Also maybe be prepared for a step back in potty training with Pumba, when he sees the new puppy peeing inside he might feel he can do it too it happens sometimes but not always.
Can't wait for pic of the "siblings"!