If you want to start your process you will need to use an start event.
If your first task collect the booking information you can send that information using the method
ksession.startProcess("process.id", parameters);
Where parameters is a Map<String, Object> that contains the information to initialize the process.
If you don't want to do that, you need to start first the process with any parameters and then present the first task to the user to complete the booking information.
Greetings.