Fix lab waiting time

src/main/java/nl/tudelft/queue/service/RequestService.java

@@ -17,6 +17,7 @@
  */
 package nl.tudelft.queue.service;
 
+import java.time.LocalDateTime;
 import java.util.*;
 import java.util.stream.Collectors;
 
@@ -152,6 +153,9 @@ public class RequestService {
 	@Transactional
 	public void takeRequest(LabRequest request, Person assistant) {
 		var event = rer.applyAndSave(new RequestTakenEvent(request, assistant.getId()));
+		if (request.getEventInfo().getFirstProcessedAt() == null) {
+			request.getEventInfo().setFirstProcessedAt(LocalDateTime.now());
+		}
 		qps.notifyAssistantComing(request, assistant);
 		wss.sendRequestTaken(event);
 		wss.sendRequestPositionUpdate(request, request.getSession().getQueue());