Hi,
Inside the confirm button, you can add the code to create timesheet record, what you have to do is,  prepare a dict of value and pass it to the create method of time sheet model.

vals = {'field_1': field_value, 'field_2': field_value}
self.env['account.analytic.line'].create(vals)


Sample code:

timesheet_entry = self.env['account.analytic.line'].create({
    'project_id': self.project_customer.id,
    'task_id': self.task1.id,
    'name': 'my only timesheet',
    'unit_amount': 4,
    'user_id': self.user_employee.id,
})

Odoo ORM Create:   https://www.youtube.com/watch?v=n37RL_j4K3A

Thanks