I dunno, but I wouldn’t be surprised if the answer is “not long”. Especially if they still conquer Aquitaine and Burgundy, they’ll probably need to convert to appease their subjects. I also remember that the Church was pretty important in administration? Anyways, it’s probably not pragmatic not to convert at this point. You’d just be surrounding yourself with hostile neighbors, alienating your subjects, and alienating the Church.
An impact might also be made in which branch the Franks convert to. IIRC, Clovis’s wife influenced him to convert to Catholicism. There’s a possibility that they convert to Arianism instead, which would have implications down the road.
I think it’s too soon to tell how this affects Saxony and the Germanic tribes. Even IOTL, it was hundreds of years after Clovis’s death that concerted efforts to convert Saxony were made, and even those were bloody and difficult. Many events could happen after the PoD to influence when and if the rest of Europe converts.