src/main/java/io/reactivex/Completable.java
@CheckReturnValue
    @Experimental
    @SchedulerSupport(SchedulerSupport.COMPUTATION)
    public final Completable delaySubscription(long delay, TimeUnit unit) {
        return delaySubscription(delay, unit, Schedulers.computation());
    }
@CheckReturnValue
    @Experimental
    @SchedulerSupport(SchedulerSupport.COMPUTATION)
    public final Completable delaySubscription(long delay, TimeUnit unit) {
        return delaySubscription(delay, unit, Schedulers.computation());
    }
Returns a Completable that delays the subscription to the source CompletableSource by a given amount of time.
<p>
<img width="640" height="475" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/Completable.delaySubscription.t.png" alt="">
<dl>
<dt><b>Scheduler:</b></dt>
<dd>This version of {@code delaySubscription} operates by default on the {@code computation} {@link Scheduler}.</dd>
</dl>

@param delay the time to delay the subscription
@param unit  the time unit of {@code delay}
@return a Completable that delays the subscription to the source CompletableSource by the given amount
@since 2.2.3 - experimental
@see <a href="http://reactivex.io/documentation/operators/delay.html">ReactiveX operators documentation: Delay</a>