When will Imam al-Qaim (atfs) reappear?

حدثنا جعفر بن محمد بن مسرور رحمه الله قال: حدثنا الحسين بن محمد ابن عامر، عن عمه عبد الله بن عامر عن محمد بن ابى عمير عمن ذكره عن ابى عبد الله عليه السلام قال: قلت له ما بال أمير المؤمنين " ع " لم يقاتل فلانا وفلانا وفلانا؟ قال لآية في كتاب الله عزوجل: (لو تزيلوا لعذابنا الذين كفروا منهم عذابا اليما) قال قلت وما يعني بتزايلهم؟ قال ودائع مؤمنين في أصلاب قوم كافرين وكذلك القائم " ع " لن يظهر ابدا حتى تخرج ودائع الله تعالى فإذا خرجت ظهر على من ظهر من اعداء الله فقتلهم.

The narrator said, I said to Abu Abdullah Imam Sadiq (ع), "What is the matter that Amir Al-Momineen (ع) did not fight against so and so, and so and so, and so and so?"

The Imam (ع) said, "Due to a Verse in the Book of Allah (عز وجل), "Had they been widely separated one from another, We would surely have Punished those who disbelieved from among them with a painful Punishment" (48:25).

I (the narrator) said, "What is the meaning of being separated from them?"

The Imam (ع) said, "Deposits of the Believers in the loins (Sulb) of the disbelieving people. And such is the case that al-Qaim (ع) would not appear, ever, until Allah (تعالى) extracts the deposits (i.e. all believers to be born out of disbelievers). So when these come out, He would get the upper hand over the enemies of Allah (عز وجل), so He (ع) would kill them".

[Source: Illal Sharaye - Shaikh Sadooq Vol. 1, Chapter 122, Hadith. 2]