Hi I have few questions please answer as accurate and quick as possible

1) Is this important to send the affidavit of support before the form Ds-230?
2) Since I have stated working this month and this is my first job therefore I don't have the tax returns of the previous 3 years which are required to overcome I have to add a joint sponsor who can show tax returns in that case am I still the sponsor?
3) In this case what box do I need to check on the affidavit of support?
I am the petitioner. I filed or am filing for the immigration of my relative
OR
I am the ( ) first sponsor ( ) second of two joint sponsor
4) And what box should the other sponsor check
I am the only joint sponsor
OR
I am the ( ) first sponsor ( ) second of two joint sponsor