[devy]

No. WeChat started from scratch. None of the QQ users were ported to WeChat on day 1. You had to create a different account based on your mobile phone number just like any other mobile apps. You can, of course, use QQ credentials to login AFTER you created your WeChat account but you still have to create a WeChat account first and then link it to QQ. None of 650MM users were automatically created initially AFAIK. It was a "bold move" to cannibalize Tencent's own users in a way, after all.

[anuh]

Agreed. You could not import QQ contacts and in fact you could only add QQ contacts who were already on WeChat as "friends". So you had to discover WeChat on your own and could not invite a QQ user who had not yet discovered WeChat to join as a friend. WeChat did not ever push import all contacts from QQ to WeChat.