I have a homemade styrobator. My temps with my first hatch fluxuated between 97 and 104 (yikes). I had sat a dozen eggs. 2 were infertile and 1 was an early death. The other 9 were successful hatches. I am currently in my 2nd round. My bator has hovered between 97-102 consistently (yaay), I sat a dozen eggs. 2 were early death. 5 have hatched, 3 are pipped externally and 2 pipped internally on day 21. I wouldnt worry about the fluxuation too muchJust make sure it stays pretty consistent.
You give me hope that I won't ruin this batch. I still feel horrible about my first one.