Should I ask for a raise in my first day of work?
That sounds risky. Is there a reason why you want a raise?
I'm a designer and the work is going to be too boring without a raise.
Your salary has been finalized just recently, so it looks bad for you if you try to change things so soon. It makes you look greedy and/or indecisive to ask for a raise so soon.
I'm going to ask. And then I'm going to keep asking until I get a yes.
I think that is a mistake. You might not even be able to continue working by trying to renegotiate after coming to a decision before you started working.