Hi there!
I'm not going to harangue you about your choice to breed, but I do feel you should be as informed as possible.
Winnie's first heat may be a silent heat (may not have a lot of visible signs). At 8 months she may be close to it or she may have already had it. But I would never recommend breeding this young - but you did mention eventually.
We waited until our girl was 2 yrs old. It gave us plenty of time to begin showing her, assessing her conformation, and make sure she was healthy without genetic defects.
And even then after all of our careful preparations & health screening, sometimes things don't go as planned. DDBs can have problems with breeding. Many males are too heavy for the female to support - so AI is needed. Just so you know, DDBs often have c-sections - the pups are very large at birth. Our female, Hanna, needed a c-section for a 'stuck puppy'.
Anyways, glad you like your girl. They are wonderful dogs.