currently, no. You would need to wait until tealium is initialized before the first call. We're working on supporting this in a future update. There is an optional completion handler you can specify when initializing Tealium, so you could buffer your calls in a queue, and then use the completion handler to clear the queue when the Tealium object has initialized.
Check out our new Swift integration library for iOS, macOS, tvOS and watchOS: https://github.com/Tealium/tealium-swift with updated