reactor-core/src/main/java/reactor/core/publisher/Mono.java
public final <U> Mono<T> delaySubscription(Publisher<U> subscriptionDelay) {
		return onAssembly(new MonoDelaySubscription<>(this, subscriptionDelay));
	}
public final <U> Mono<T> delaySubscription(Publisher<U> subscriptionDelay) {
		return onAssembly(new MonoDelaySubscription<>(this, subscriptionDelay));
	}
Delay the subscription to this {@link Mono} until another {@link Publisher}
signals a value or completes.

<p>
<img class="marble" src="doc-files/marbles/delaySubscriptionWithPublisherForMono.svg" alt="">

@param subscriptionDelay a
{@link Publisher} to signal by next or complete this {@link Mono#subscribe(Subscriber)}
@param <U> the other source type

@return a delayed {@link Mono}