The Periplus of the Erythraean Sea gives sailing times along the Rea Sea coast and along the Indian coast, but not across the Arabian Sea. There were a number of ports on both sides, 1-3 days sailing apart.
Pliny says that the voyage from Ocelis (on the Red Sea) to Muziris (in southern India) would take 40 days – but that would include a few stops along the way. We don’t know the precise location of Ocelis, but it was somewhere close to Muza towards the south of the Red Sea. There would have been stops along the southern Arabian coast before setting out to India, probably from Cana.
Later Islamic sources say the journey took 2-4 weeks from the southern Arabian coast to India.
Quantity of trade…
In The Roman Empire and the Indian Ocean (2014), Raoul McLaughlin estimates (from surviving sources) that there were about 120 large ships a year trading between Egypt and India. [EDIT: I see that am77494 already said that above.]
These were big merchant ships, with a capacity of 350-500 tons of goods. There may have been many smaller vessels as well.