Yue Lan was still busy with her normal schedule, so she wasn't able to go with him right away. Not to mention that if they were to go now, they would attract a lot of attention.
This was something that they needed to keep secret until the time was right, so it was best if they didn't attract any attention that they didn't need to attract.
In the end, they made the decision to head out of the town to check out the iron vein after dinner when it got darker. The excuse that they would give others would be an after dinner walk and date.
Yue Lan really didn't have much time, so after setting this, she quickly headed off to take care of her normal duties.
