There may be surgery out there that can make the voice lower, but T does most of the work. As far as completely cosmetic plastic surgery and voice surgery for FTMs, I wouldn't recommend even thinking about it until 5 years on T. That is the typical length of puberty. It may go faster if you have a hysterectomy at some point along the line, but in general 5 years is about when you can expect most of your changes to have occurred and your body to be about what it will be.
Speech therapists however may be useful in terms of breaking female speech patterns. I've found it's helpful to watch videos of guys speaking to get a feel for what to do/what to avoid, but some people may need more hands on help.