Hey Chanel! Thanks for joining us!
One of the challenges with email is that it's not necessarily a real time medium. It wasn't designed to be an instant messaging channel, and delivery can take time. Mailbox providers are dealing with a ton of concurrent traffic and realistically can't deliver all the mail they receive at one time, so you should anticipate some delays, especially if you're increasing volume/frequency, dealing with an existing reputation, or sending to less-viable audiences than usual.
Caveats aside, the best places to look are your analytics like email channel engagement, the Deliverability Center, and campaign performance. If deliveries stagnate below 98%, if bounces exceed 2%, or complaints are over 0.01%, it's time to pause and recalibrate. Similarly, a decrease in IP or domain reputation Google Postmaster Tools or Microsoft SNDS are signals that you're not reaching the right addresses, or those addresses aren't fond of what you're sending. You don't have to stop or change your plans completely, but you should be aware that continued sending without making changes can have detrimental effects on your sender reputation.
Of course, if you have Braze's Deliverability Services, we'd keep an eye on that for you and reach out if there's reason to be concerned!