In general –
Order your Social Media Background Check later in the recruiting process, and ideally AFTER you have made a conditional job offer.

This mitigates exposure to EEOC problems where recruits might claim that they were eliminated from consideration once your company was aware of their demographics.

When you use an applicant’s or employee’s background information to make an employment decision, regardless of how you got the information, you must comply with federal laws that protect applicants and employees from discrimination. This includes discrimination based on race, color, national origin, sex, or religion; disability; genetic information (including family medical history); and age (40 or older). These laws are enforced by the Equal Employment Opportunity Commission (EEOC).

Employers may be exposed to this early in the recruiting process, but this “protected status discrimination” claim is much weaker later on, when the demographics are ancient history.

In-house recruiters often do quickie Social Media Background Checks early-on to perhaps quickly eliminate bad-apples, but this practice can obviously lead to trouble.  These searches are often inconsistent too, which is also not allowable (e.g., quickie background reports are run more frequently and in greater depth on women vs. men).

Take-away: when it comes to Social Media Background Checks – do procrastinate, do it right, and be consistent.