By default an email sent the moment your subscriber reaches the step. What if they reach this step on a weekend, and you only want to send on weekdays?

All you have to do is add a "Wait" step beforehand. This is how you tell the automation step "Wait, before you proceed, make sure some conditions are met"

In the settings for the "Wait" step, you will want to enable time and day control, like so:

Then, you will want to choose your time window, and days of the week:

If you're only interested in limiting by day, you could choose the entire timespan from midnight to midnight. However, it's generally a good idea to make use of the time window feature and also select time of the day when they're more likely to open.