My principal doubt is, if Girona after this international break is gonna still being this good, or they are gonna start to fall behind, maybe they can last until the winter break, and become the winter champions 
i remember the alst team becoming winter champion asides of the big threes was Real Sociedad a lot of time ago.
I think some people would have the same doubts as you, including myself. Not to underestimate them, but from our experience in La Liga, that teams that can surprise at the beginning of the season they will not be able to maintain until the end of the season, and that always happens, and maybe we can see from the past few seasons that there are always teams that can provide a surprise but at the end of the season it is still the 3 teams that are in the top 3, Real Madrid, Barcelona and Atletico Madrid. This may also be felt by other teams, one of which is Girona who are now at the top of the table. i remember the alst team becoming winter champion asides of the big threes was Real Sociedad a lot of time ago.Although I also doubt Girona will be able to stay at the top of La Liga until the end of the season, but it seems that I little hopeful that Girona can make a big surprise this season. Because after all, although previously teams like Betis and Real Sociedad had the same case of being good at the beginning of the season and then falling. But at least, Betis and Real Sociedad managed to compete at least in the top 6 or in the top 5 in previous seasons as well. But about Girona, who haven't always been in the top 6 in every season, but this season Girona are quickly in contention for the title. So ya, it's been a big surprise this season, even though there are no guaranteed trophies for Girona but still, Girona have managed so far this season in the top La Liga standings, and I hope Girona can keep it up. Who knows