diff --git a/src/controllers/sessionController.ts b/src/controllers/sessionController.ts
index 2f9bf91..a871b77 100644
--- a/src/controllers/sessionController.ts
+++ b/src/controllers/sessionController.ts
@@ -1,4 +1,5 @@
 import { Request, Response } from "express";
+import { addMinutes, formatISO } from "date-fns";
 import ActiveSession from "../models/ActiveSession";
 import SessionServer from "../models/SessionServer";
 import Build from "../models/Build";
@@ -21,7 +22,11 @@ export const startSession = async (req: Request, res: Response) => {
   const location = req.query.location as string;
   const buildName = req.query.build as string;
   const ownerIp = req.headers["x-real-ip"];
-  const endAt = req.query.endAt as string;
+  const endAtParam = req.query.endAt as string | undefined;
+  const DEFAULT_SESSION_DURATION_MINUTES = 30;
+  const endAt = endAtParam
+    ? endAtParam
+    : formatISO(addMinutes(new Date(), DEFAULT_SESSION_DURATION_MINUTES));
   let type = req.query.type as string;
   const userRegion = req.headers["x-user-region"] as string;
 
@@ -67,7 +72,7 @@ export const startSession = async (req: Request, res: Response) => {
   }
 
   const sessionServers = await SessionServer.find({ location, type }).sort({
-    gpuMemoryFree: -1,
+    gpuMemoryUsed: 1,
   });
 
   if (sessionServers.length === 0) {
@@ -76,9 +81,11 @@ export const startSession = async (req: Request, res: Response) => {
   }
 
   for (const sessionServer of sessionServers) {
-    const gpuMemoryFree = sessionServer.gpuMemoryFree!;
+    const gpuMemoryTotal = sessionServer.gpuMemoryTotal ?? 0;
+    const gpuMemoryUsed = sessionServer.gpuMemoryUsed ?? 0;
+    const gpuMemoryAvailable = gpuMemoryTotal - gpuMemoryUsed;
 
-    if (gpuMemoryFree < build.gpuMemoryUsed!) {
+    if (gpuMemoryAvailable < build.gpuMemoryUsed!) {
       continue;
     }
 
@@ -87,11 +94,13 @@ export const startSession = async (req: Request, res: Response) => {
     console.log("endAt", endAt);
 
     try {
+      const startAt = formatISO(new Date());
       const result: any = await got
         .post(`${sessionServerUrl}/start`, {
           json: {
             buildName,
             ownerIp,
+            startAt,
             endAt,
           },
         })
diff --git a/src/models/ActiveSession.ts b/src/models/ActiveSession.ts
index 3657f08..dd3ab7f 100644
--- a/src/models/ActiveSession.ts
+++ b/src/models/ActiveSession.ts
@@ -32,6 +32,9 @@ const activeSessionSchema = new Schema(
     connectedPlayersCount: {
       type: Number,
     },
+    startAt: {
+      type: Date,
+    },
     endAt: {
       type: Date,
     },
diff --git a/src/models/SessionServer.ts b/src/models/SessionServer.ts
index 428fc18..0381240 100644
--- a/src/models/SessionServer.ts
+++ b/src/models/SessionServer.ts
@@ -15,7 +15,10 @@ const sessionServerSchema = new Schema(
       type: String,
       unique: true,
     },
-    gpuMemoryFree: {
+    gpuMemoryTotal: {
+      type: Number,
+    },
+    gpuMemoryUsed: {
       type: Number,
     },
     localIP: {
diff --git a/src/services/cronService.ts b/src/services/cronService.ts
index 135c0c1..36c0b43 100644
--- a/src/services/cronService.ts
+++ b/src/services/cronService.ts
@@ -1,16 +1,20 @@
 import ActiveSession from "../models/ActiveSession";
 import got from "got-cjs";
-import { differenceInMinutes, isAfter } from "date-fns";
+import { differenceInMinutes, isAfter, parseISO } from "date-fns";
 
 export async function checkActiveSessions() {
   const activeSessions = await ActiveSession.find();
+  const now = new Date();
 
   for (const activeSession of activeSessions) {
-    if (
+    const shouldEndByEndAt =
+      activeSession.endAt && isAfter(now, activeSession.endAt);
+    const shouldEndAsOrphan =
       !activeSession.endAt &&
       !activeSession.connectedPlayersCount &&
-      differenceInMinutes(new Date(), activeSession.updatedAt) >= 3
-    ) {
+      differenceInMinutes(now, activeSession.updatedAt) >= 3;
+
+    if (shouldEndByEndAt || shouldEndAsOrphan) {
       const activeSessionId = activeSession.id;
 
       try {
@@ -39,7 +43,7 @@ export async function checkScheduledSessions() {
 
     for (const session of scheduledSessions) {
       if (
-        isAfter(new Date(), new Date(session.startAt)) &&
+        isAfter(new Date(), parseISO(session.startAt)) &&
         !session.activeSessionId
       ) {
         console.log("session.buildId", session.buildId);
@@ -69,7 +73,7 @@ export async function checkScheduledSessions() {
           .json();
 
         console.log("result2: ", result2);
-      } else if (isAfter(new Date(), new Date(session.endAt))) {
+      } else if (isAfter(new Date(), parseISO(session.endAt))) {
         const result = await got
           .post(`https://coord.graff.tech/end`, {
             json: { activeSessionId: session.activeSessionId },