diff --git a/src/PrismaQueue.ts b/src/PrismaQueue.ts
index e27c25c..18179ed 100644
--- a/src/PrismaQueue.ts
+++ b/src/PrismaQueue.ts
@@ -202,7 +202,7 @@ export class PrismaQueue<
         continue;
       }
       // Query the queue size only when needed to reduce database load.
-      let estimatedQueueSize = await this.size();
+      let estimatedQueueSize = await this.size(true);
       if (estimatedQueueSize === 0) {
         await waitFor(pollInterval);
         continue;
@@ -269,8 +269,8 @@ export class PrismaQueue<
              SELECT id
              FROM ${tableName}
              WHERE (${tableName}."queue" = $1)
-               AND (${tableName}."runAt" < NOW())
                AND (${tableName}."finishedAt" IS NULL)
+               AND (${tableName}."runAt" < NOW())
                AND (${tableName}."notBefore" IS NULL OR ${tableName}."notBefore" < NOW())
              ORDER BY ${tableName}."priority" ASC, ${tableName}."runAt" ASC
              FOR UPDATE SKIP LOCKED
@@ -339,10 +339,16 @@ export class PrismaQueue<
     return job;
   }
 
-  public async size(): Promise<number> {
+  public async size(onlyAvailable?: boolean): Promise<number> {
     const { name: queueName } = this;
+    const date = new Date();
+    const where: Prisma.QueueJobWhereInput = { queue: queueName, finishedAt: null };
+    if (onlyAvailable) {
+      where.runAt = { lte: date };
+      where.AND = { OR: [{ notBefore: { lte: date } }, { notBefore: null }] };
+    }
     return await this.model.count({
-      where: { queue: queueName, finishedAt: null },
+      where: { queue: queueName, finishedAt: null, runAt: { lte: date } },
     });
   }
 }