Quick Short Question

hello, I’m relatively new to burning and advance burning. I have nero 7, which starts off when i burn really low then gradually builds up to the 12x its supposed to burn. So my question is, Is it supposed to start off gradually slow then work its way up in speed of the burning?

for example its starts of at 3.3x (around there) then works its way up to 11.8x, burning a files with a total of 4.3GB. Is that supposed to happen?