Another trans guy I know (a younger guy) asked about T and I told him I would ask around. He wants to know how long it takes approximately for one's voice to change on the cream.

I dont kno bout cream necessarily but im on androgel and my voice dropped some bout 3months in...then a lot bigger drop around 6months came...its still not as deep as id like it to be and im sure it is going to drop more but it is in a tenor male range now i think

Depends a lot on dose and so on. I think a lot of guys go on it to start kind of low dose.
I believe voice is one of the first changes anyway and even happens for people on low dose.

--Jay

Depends on the person, their dose, and how well that dose works for them as well as how their body processes the T. 

Long story short: there is no definitive answer.

What WTAD said is true. I found that my voice changed probably about two months in, but only slightly. For me the change was very gradual.

K thanks. I'll pass that info on.

I started out on testrogel.
already the first few weeks I could feel my voice where changing, (cause I sang)
you couldn't hear it much but it felt strange like if you had a flu.
then in around 3 months I could hear the changing in my voice.

so to give a direct answer it happent's very fast but your might first be able to really hear a clear diffrence in a couple of months.