Rows and rows, bottle upon bottle. Thousands of Cantillon Bio gueuze bottles refermenting and resting before they go on sale. About 6 months of horizontal resting to have a good bottle refermentation is the time needed but actually ‘They’re ready when they’re ready ‘is a better answer to the ‘How long’ question. Even then a bottle might not be ready or not to your taste. Give it some more rest in a cellar or an appropriate space. The lambic will evolve for many more years…..