When a capability-matched node is busy executing other test scripts, the latest test script will wait for the node to be available. By default, there is no wait timeout; that is, the test script will wait for the node to be available indefinitely. To alter that behavior and to let the test script throw an exception if it doesn't get the node within a limited time, Selenium Grid opens a configuration that enables the test script to do so. The configuration parameter controlling that behavior is newSessionWaitTimeout. The command for that is as follows:

java -jar selenium-server-standalone-3.12.0.jar -role hub -port 1111 -newSessionWaitTimeout 120000

Here, the test script will wait for two minutes before it throws an exception saying it couldn't obtain a node to execute itself.