Sometime around 6:30 p.m. tonight, the Royals will be on the clock with a 41/2-minute window to make the eighth selection in Major League Baseball’s annual First-Year Player Draft.

They can only guess, at this point, who might be available.

The early round, particularly picks at the top of the first round, often hinges on signability issues and the restrictions imposed by the signing bonus pool allotments. For these picks, intrigue is often an integral part of the process.

Or as Royals assistant general manager J.J. Picollo said: “One pick can throw the whole thing into a tailspin with this system in place.”

All sorts of questions exist among the top-rated prospects.

For example: Most scouts cite college pitchers Jonathan Gray (Oklahoma) and Mark Appel (Stanford) as the top two prospects.

But Gray recently tested positive for Adderall, a legal stimulant but one banned by baseball without a prescription, and Appel rejected a slotted offer last year from Pittsburgh by returning for a senior season to Stanford. His adviser, Scott Boras, continues to push for an above-slot bonus.

A team can over-pay Appel but doing so reduces its bonus-pool dollars for subsequent picks. It remains uncertain what, if any, leverage Boras has in negotiating for Appel, but clubs might opt to avoid the headache.