Requirement for reverse charge

No RCM , as u sell u have charge GST & deposit

you have to collect gst from customer and pay to gov.. no need to pay RCM cause you not pay any tax on it so you cant claim ITC...

[a] a person who has applied for registration under this Act within thirty days from the date on which he becomes liable to registration and has been granted such registration shall be entitled to take credit of input tax in respect of inputs held in stock and inputs contained in semi-finished or finished goods held in stock on the day immediately preceding the date from which he becomes liable to pay tax under the provisions of this Act;

means the person can sell and issue the invoice for the same without having purchasr invoices

For availing ITC the first condition to be fulfilled is that the registered person should possess the invoice issued by the supplier.