You should have contacted hdfc customer care when you received your card and asked them 90 days spend criteria to make it LTF.
I am not sure if it will become LTF now. Maybe ask them if there is anyway to make it LTF.
Try emailing to customer care. They took 1 week time to accept my request. But in my case I had applied for add-on cards within 1week of recieving primary card.