Potty training in an apartment

me again with all of the questions!

I’m getting a puppy on Saturday and I live on the second floor of my apartment.

The puppy will be 8-9 weeks old. And still too young to be fully vaccinated. We have a balcony, but it isn’t a solid floor - it’s a bunch of wooden slats spaced apart (but pretty close). I’ve looked into those real grass patches, but they are really expensive. If they worked for anyone else though, I’d love to talk more about it because I have so many questions!

My biggest worry is getting her downstairs to a potty spot in time - especially in the winter and with her likely not being used to stairs yet. Any advice on the best way to potty train her?