You have asked your query from a legal point of view only. In that case, I recommend you refer to the Payment of Wages Act, 1936. I doubt whether your proposal will stand scrutiny of this act.
Management Science Perspective
I would like to go a little further and handle this case from a management science point of view. When would you like to disclose these conditions of employment to the job candidates? Once these conditions are disclosed, do you think that you will attract talented candidates? Will a job candidate who is quite confident of getting the job and who also has a high level of self-esteem join under these conditions?
The unsaid part of your post is that your organization could be facing a problem of attrition of newly joined employees. To mitigate the expenses of employee exits, you have tried pulling this rabbit out of your hat. But then, if this policy comes into effect and if some talented job candidate refuses to join, what will be the cost of lost opportunities; have you measured that?
If employees are not sticking, then your problem could be with your organization's culture or your leadership. Please fix either or both of the problems. If other companies are able to retain employees, then so should you. Study your organization's ills and take remedial measures rather than finding unconventional solutions.
Case Study: Photo Studio
My experience: I conducted training for the staff of one major photo studio. They had a similar problem. The owner went to the extent of withholding salary for the first two months. Even then, attrition did not decrease. Those who wanted to leave did so anyway, without bothering about the loss of two months' salary.
Thanks,
Dinesh V Divekar