If I did not register and did not collect GST (Goods & Service Tax) from the customers, will my registration date be backdated?

Yes, your GST (Goods & Service Tax) registration date will be backdated to the date when you become liable for GST. You will be required to account for and pay it on all the taxable supplies commencing from the date the liability arises, even if you did not collect it from customers. You may face a penalty for late registration.

Therefore it is important to keep proper accounting records and apply GST registration in time.