When should we stop using an indoor grass patch for our puppy?

Hi everyone,

I live in a flat and we currently use a portable grass patch on our balcony for our puppy to use as a toilet. He’s 12 weeks old and now fully vaccinated, so we’ve started taking him out for walks.

I’m wondering whether we should start weaning him off the grass patch at home and gradually encourage him to do his business outside on walks instead, or if it’s better to keep the grass patch for now while he’s still young.