Yep, January will be high season there – best value will be had by booking as far in advance as you can (seats are released 11 months in advance).
Sometimes airlines will launch tactical sales for off-peak travel which might provide lower prices than the lowest (standard) fares you could book when the seats first come on sale. So, for e.g., BA often have a seat sale in January and September. If you were planning to fly on BA to (say) the Caribbean in May/June, your best bet would be either picking up the cheap seats when they come on sale in the previous June/July, or hoping that there is capacity left for route you want and the airline offer some reductions in January.
In your case, travelling high season, you won’t gain anything by leaving it – shop around for the best fare you can find and book it right away if you can. Fares won’t differ much from one broker to another.