Correct, there's just no guarantee that you would receive your...

Correct, there's just no guarantee that you would receive your full allocation of shares if the SPP was oversubscribed and subject to a scaleback. It's a calculated risk at your own discretion, as a general example, if you sold $15k worth of shares at tomorrow's open then applied for $15k in the SPP, if it was scaled back you might only receive $12k worth and be refunded the difference.

This is not financial advice, dyor.