Yesterday, Government of India announced that the special requirement for online sellers to be compulsorily registered under GST has been deferred until further notice. So as of now, there is no difference between selling offline and selling online. All exemptions available to offline sellers are available to online sellers as well.
In simple words, you can continue doing business as you were doing before GST. You have more time to get your GST registration and learn how to file GST Tax.
We recommend that you apply for your GST ID right away to be ready when government announces a date for implementation of GST for online sellers.