diff --git a/estore/src/app/api/checkout/route.ts b/estore/src/app/api/checkout/route.ts
index 0789e71..4438e34 100644
--- a/estore/src/app/api/checkout/route.ts
+++ b/estore/src/app/api/checkout/route.ts
@@ -87,6 +87,9 @@ export async function POST(req: NextRequest) {
   if (customerLastName && (typeof customerLastName !== 'string' || customerLastName.length > 100 || /[\r\n\x00-\x1f]/.test(customerLastName))) {
     return NextResponse.json({ error: 'Invalid last name' }, { status: 400 })
   }
+  if (deliveryAddress && !deliverySlotISO) {
+    return NextResponse.json({ error: 'A delivery time is required when scheduling a delivery.' }, { status: 400 })
+  }
 
   const customerName = [customerFirstName, customerLastName].filter(Boolean).join(' ') || undefined
 
diff --git a/estore/src/lib/square.ts b/estore/src/lib/square.ts
index 83347c7..2d89153 100644
--- a/estore/src/lib/square.ts
+++ b/estore/src/lib/square.ts
@@ -280,7 +280,7 @@ export async function createSquareOrder(params: {
               phoneNumber: params.fulfillment.recipientPhone,
               address: { addressLine1: params.fulfillment.addressLine1 },
             },
-            scheduleType: 'SCHEDULED',
+            scheduleType: params.fulfillment.deliverAt ? 'SCHEDULED' : 'ASAP',
             ...(params.fulfillment.deliverAt              ? { deliverAt:              params.fulfillment.deliverAt }              : {}),
             ...(params.fulfillment.deliveryWindowDuration ? { deliveryWindowDuration: params.fulfillment.deliveryWindowDuration } : {}),
             ...(params.fulfillment.note                   ? { note:                   params.fulfillment.note }                   : {}),