As often as you like. Or as little as you like. Your account itself is a free, zero-balance account. 

If you are making your investment using netbanking you can transact freely, as long as you have sufficient cash in your bank account.

You can also automate your investment schedule, if you choose. 

We’ve set it up so you can schedule an investment every month or every quarter. 

If you need to make two investments in a month, simply set up two separate instructions, each 15 days apart.