Plan for Concurrent Users

Hi,

For one of our projects - the customer has 30K users in same time zone -

The SP2013 site is supposed to be set as default IE home page (Main Intranet Portal) -

For now there is no existing application that would give a good sense of how many concurrent users to expect -

Two questions -

1) Can some one help with some reference numbers for how many concurrent users to expect or good pointers?

2) I have read in articles that a given WFE - 4 cores 16GB RAM VM - would be typically be able to handle 300 concurrent users load? Is that a good assumption?

-http://lrathi.blogspot.com