I heard your voice in that other thread, it's sounding fine.
On when it "becomes" your natural voice without thinking about it? It took me about maybe 6 months of constant use to get where I never think about it, I just talk. I was living full time and NEVER use my guy voice which helps. I would think for people who have to switch back and forth, it would be easy to slip back into your guy voice.. One thing that would happen at first was: I would start off sounding female and in a longer conversation, especially if it was something serious or required a lot of thought I would slip into my old voice. I asked close friend to like "raise your hand and tell me -guy voice-" if I did this. IDK if it was because my female voice would tire out or multitasking of thinking about how I am speaking plus the subject required too much though was the cause, I'm not sure. Just be aware of that.