Fixed mortgage early renewal

Apologies if this is being asked often or a stupid question but I can’t seem to find the right answer

I’m with RBC and they offer 6-month early renewal for fixed mortgage. Does it mean 6 months prior to my 2-year fixed rate, I can start using the new rate? Or it just means I can lock in a new rate 6 months prior, and I can only use the new rate when the two years term is done?

Asking this becoz we got the 2 years fixed by end of 2023 and now rates are lower, seeing if we can take advantage of the lower rate earlier instead all the way to 2025 end