diff --git a/app/models/enrolment/ExamEnrolment.java b/app/models/enrolment/ExamEnrolment.java
index 5c612af20..96805a626 100644
--- a/app/models/enrolment/ExamEnrolment.java
+++ b/app/models/enrolment/ExamEnrolment.java
@@ -33,7 +33,7 @@
 @Entity
 public class ExamEnrolment extends GeneratedIdentityModel implements Comparable<ExamEnrolment> {
 
-    private static final int DELAY_MAX = 30;
+    private static final int DELAY_MAX = 30 * 1000;
 
     @ManyToOne
     @JsonManagedReference
diff --git a/app/repository/EnrolmentRepository.java b/app/repository/EnrolmentRepository.java
index 49c93d7a9..15d71f4c2 100644
--- a/app/repository/EnrolmentRepository.java
+++ b/app/repository/EnrolmentRepository.java
@@ -288,11 +288,6 @@ private void handleUpcomingEnrolment(
             if (
                 enrolment.getExam() != null && enrolment.getExam().getImplementation() == Exam.Implementation.AQUARIUM
             ) {
-                // If user is on a correct aquarium machine then always set a header
-                headers.put(
-                    "x-exam-aquarium-login",
-                    String.format("%s:::%d", getExamHash(enrolment), enrolment.getId())
-                );
                 // Aquarium exam, don't set headers unless it starts in 5 minutes
                 DateTime threshold = DateTime.now().plusMinutes(5);
                 DateTime start = dateTimeHandler.normalize(
@@ -327,22 +322,22 @@ private boolean isInsideBounds(ExamEnrolment ee, int minutesToFuture) {
         int delay = ee.getDelay();
         return (
             (reservation != null &&
-                reservation.getStartAt().plusSeconds(delay).isBefore(latest) &&
+                reservation.getStartAt().plusMillis(delay).isBefore(latest) &&
                 reservation.getEndAt().isAfter(earliest)) ||
             (event != null &&
-                event.getStart().plusSeconds(delay).isBefore(latest) &&
+                event.getStart().plusMillis(delay).isBefore(latest) &&
                 event.getStart().plusMinutes(ee.getExam().getDuration()).isAfter(earliest))
         );
     }
 
     private DateTime getStartTime(ExamEnrolment enrolment) {
         return enrolment.getReservation() != null
-            ? enrolment.getReservation().getStartAt().plusSeconds(enrolment.getDelay())
+            ? enrolment.getReservation().getStartAt().plusMillis(enrolment.getDelay())
             : enrolment
                 .getExaminationEventConfiguration()
                 .getExaminationEvent()
                 .getStart()
-                .plusSeconds(enrolment.getDelay());
+                .plusMillis(enrolment.getDelay());
     }
 
     private Optional<ExamEnrolment> getNextEnrolment(Long userId, int minutesToFuture) {
diff --git a/conf/evolutions/default/136.sql b/conf/evolutions/default/136.sql
new file mode 100644
index 000000000..b8340b118
--- /dev/null
+++ b/conf/evolutions/default/136.sql
@@ -0,0 +1,9 @@
+-- SPDX-FileCopyrightText: 2024 The members of the EXAM Consortium
+--
+-- SPDX-License-Identifier: EUPL-1.2
+
+# --- !Ups
+UPDATE exam_enrolment SET delay = delay * 1000;
+
+# --- !Downs
+UPDATE exam_enrolment SET delay = delay / 1000;
diff --git a/ui/src/app/enrolment/waiting-room/waiting-room.component.ts b/ui/src/app/enrolment/waiting-room/waiting-room.component.ts
index ebb2baa69..9f2175752 100644
--- a/ui/src/app/enrolment/waiting-room/waiting-room.component.ts
+++ b/ui/src/app/enrolment/waiting-room/waiting-room.component.ts
@@ -102,7 +102,7 @@ export class WaitingRoomComponent implements OnInit, OnDestroy {
     private startScheduled = () => {
         window.clearTimeout(this.startTimerId);
         const offset = Math.ceil(
-            DateTime.fromJSDate(this.getStart()).plus({ seconds: this.enrolment.delay }).toSeconds() -
+            DateTime.fromJSDate(this.getStart()).plus({ milliseconds: this.enrolment.delay }).toSeconds() -
                 DateTime.now().toSeconds(),
         );
         this.delayTimerId = window.setTimeout(this.Session.checkSession, Math.max(0, offset * 1000));