Grade or no grade the earned wages are to be paid on fixed day/date of salary.
The fixed day/date can not be later than the day/date laid down by various enactments applicable to employer/establishment/employee e.g. last day of the month/any day fixed by employer/ or maximum 7th/10th of the next month.
The employee can lodge a complaint the momment the payment of earned wages is delayed even by a day, and employer can be penalized per instance say Rs.7500/ instance.
The wage/salary slip duly signed by employer and employee has to be supplied atleast a day before the fixed day for payment of wages.
You may build irrefutable written record, under proper acknowledgment.
You can approach employee's/trade unions leaders, labor Law Consultant and proceed further under their expert guidance.
The employer that does not pay wages on time is unworthy of being employed with.
You may firm up your next venture ASAP.