Cycling confusion/odd readings

[Fox]

I am currently cycling my 33 gal tank with live rock and live sand. I started cycling it last weekend and started taking readings on Wednesday. The first time I tested for both ammonia and nitrites (rookie mistake) and the readings looked like this:
Wednesday
Ammonia:what looked like between 0-0.25
Nitrites:what looked like between 0-0.05

Thursday
Ammonia:2.5

Friday
Ammonia:0.25
Nitrites:0.05

So I thought on Thursday that my ammonia was spiking which was why I tested for nitrites again today but now I am no so sure what's going on considering I seem to back to the way it was on Wednesday. Is it more likely that I read he reading wrong or recorded incorrectly or could something else be going on normal of otherwise.

Any insight would be appreciated!