well... hopefully you won't have to wait for signs for it to be fed..

Rather you will feed it when you know that it has NOT been OVER fed...

The main sign that it needs to be fed is leaves that are not a perfect green... and slow growth

Everything else is usually a PH issue... without a perfect PH the plant does not have access to the food that is usually in the soil...

This is speaking in generalizations... of course...
There are nutrient defciencies caused by just plain lack of nutrients...

Once the plant really begins to take off you will want to make sure it has plenty of Nitrogen!!!!!

What kind of soil are you using?

: )