I think this depends on what language you're going to start learning. There is a risk that you will confuse and mix up the two but this risk is greatly reduced if the language isn't similar to French, I don't think that you would have any problems with German or Mandarin. Personally I am trying to learn French and Italian but I've decided to focus on my French for now and then when I've reached some sort of fluency start with Italian since the languages are pretty similar and I ended up confusing them a bit. This might also vary from person to person, you can always give another language a try and see if it works out or not!

I realy think that the right moment is when you feel very comfortable with your second language. At the point that all you need is a little bit of practice sometimes. At this point, when you learn a third language you will not feel like you are losing something from the previous language. I talk by my own experience, having portuguese as native and english as second language, I'm focusing now in french.

hi, how are you. I am very exited to see and know people here , i am very interested to learn cantonese & mandarin in exchange with english or may be talking on something innovative a entrepreneur may be. I am as well looking for good friends who can discuss on any topic. Are you looking forward to the same please do contact me. I live in hong kong but really find hard to communicate, you might be helpful. looking forward to hear from you until then i remain. Thank You

I can help you to learn french..contact me !

well, u can learn a third one but trust me, u will be confused... for me, i m chinese and i learnt english and french, now i always mix up something such as "fonction" and "function" etc. Also, my pronunciation get influence too.