diff --git a/telethon/network/mtprotostate.py b/telethon/network/mtprotostate.py
index 53b66306..1444ac5b 100644
--- a/telethon/network/mtprotostate.py
+++ b/telethon/network/mtprotostate.py
@@ -152,7 +152,7 @@ class MTProtoState:
         """
         Inverse of `encrypt_message_data` for incoming server messages.
         """
-        now = time.time() + self.time_offset  # get the time as early as possible, even if other checks make it go unused
+        now = time.time()  # get the time as early as possible, even if other checks make it go unused
 
         if len(body) < 8:
             raise InvalidBufferError(body)
@@ -204,8 +204,14 @@ class MTProtoState:
         #
         # This means we skip the time check for certain types of messages.
         if obj.CONSTRUCTOR_ID not in (BadServerSalt.CONSTRUCTOR_ID, BadMsgNotification.CONSTRUCTOR_ID):
+            if not self._highest_remote_id and not self.time_offset:
+                # If the first message we receive is a bad notification, take this opportunity
+                # to adjust the time offset. Assume it will remain stable afterwards. Updating
+                # the offset unconditionally would make the next checks pointless.
+                self.update_time_offset(remote_msg_id)
+
             remote_msg_time = remote_msg_id >> 32
-            time_delta = now - remote_msg_time
+            time_delta = (now + self.time_offset) - remote_msg_time
 
             if time_delta > MSG_TOO_OLD_DELTA:
                 self._log.warning('Server sent a very old message with ID %d, ignoring (see FAQ for details)', remote_msg_id)