Is this sweet to do ...?

Yes go for it!

if I have this right you are thinking of having a pizza [etc.] delivered to him on his first day at a new job. if so a BIG NO, he will be trying to 'fit in' and sending food to him would draw attention to him and his workmates will make fun of him. not what he needs if he is nervous and trying to impress.

It mainly depends on type of guy you are dating like some guys would be embarrassed of that because a women is never suppose to buy a gentleman food but i think you should do it

Whatever works... pizza is junk food tho