have&having

First of all, it should be (what time/when)
present countinus is used when an action is happening currently, else we can't use it
e.g.He is running. , The phone rings while I am doing homework.
Some hits for that.
After the word 'while' ,'be' in active voice like example 1 and verbs expressing feelings
e.g. (like,enjoy,love,hate) etc , you usually use present countinus tense.
Exception sometimes the word may be put before to (I like to swim) expresses different meanings with I like swimming.

You use having when you are saying he/she is having something.
Example: I am having ice-cream. = I am eating ice-cream NOW

Using have: I have ice-cream at my friend house. = I ate the ice-cream BEFORE NOT NOW.

having meanning something we are doing.
example: John came in the restaurant while we are having our dinner. -we are still eating.