Does it matter who I tell first when I decide to start selling my business?

Yes, it genuinely matters, both legally and practically. If you have a shareholders' agreement, a spouse with an ownership or financial interest, or partners whose consent may be needed to sell, they may need to know before anyone else, not as a courtesy but because their formal involvement may be legally required to move forward at all.

Beyond who's legally required to know, the order still matters practically. Telling employees before you've told key business partners, or telling a casual acquaintance who happens to know a buyer before you've spoken with your own lawyer, can result in information reaching people you didn't intend before you've protected yourself with confidentiality agreements or figured out your own position. Word that a business might be for sale tends to travel faster than owners expect, and it's very difficult to walk back once it starts moving through customers, suppliers, or competitors.

A sensible order is usually: confirm who is legally required to be involved, bring in a lawyer to help structure confidentiality, then decide deliberately, rather than reactively, who else needs to know and when, based on their role rather than convenience or comfort.