I will answer your question: if the James Webb Telescope finds galaxies beyond 14 billion light-years, then cosmologists will certainly revise some key points in the chronology of the Big Bang.
You might want to remember a nice saying: "Cosmologists might be wrong but they're never in doubt". This means that cosmology is our best theoretical guess given by a plain extrapolation of current known law of Physics through the use of Mathematics and actual observational datas. Once the observational datas change, obviously also the extrapolation derived from those changes.