Thank you for reaching out to Constant Contact API Support.
When you create a bulk import activity, that activity will queue and then process. There are multiple factors that go into how long it takes to process an import, such as how many contacts you are importing or how many other imports across other accounts are running.
The response to your call to create the import activity should include an activity ID ("id"), and you can make a call to get that activity by ID to see the status.
Please let me know if you have any other questions!
Regards, David Bornstein Tier II API Support Engineer