Input current for boost converter
I would make this a comment but I can't (yet).

Your procedure is correct. You have to keep in mind that the efficiency value varies among different ICs, Vin, Vout, temperature... so take it as a very good estimation which is probably enough for most purposes.

Edit: The input current you would be calculating is an average value. Also, you can only do this simple calculation if Vin has negiglible ripple.