your testing levels will fluctuate quite a bit during your cycle. Don't buffer your ph
at this point and don't add any other additives at this point either.
for the water change, was you LR
cured or uncured? If your LR
was already cured then I would also reccomend not doing a water change as the cycle requires that ammonia spike as well as the spike and drop off of both nitrites and nitrates. Once you're ammonia drops to zero your nitrites will rise. Then they will begin to fall and nitrates will rise. Eventualy, your nitrates will begin to fall and this is when most suggest you do a large water change, up to 50%.
if you are curing your LR
as well, then you will want to do water changes during your cycle.