Questions on Molting

So, I've had my little guy for about a month and a half now. He's normally quite inquisitive. Pictures will follow at some point, but right now I'm a bit rushed.

For the last four days I've not seen him. He's not even inside the entrance of his favorite hide, which leads me to believe he's entered his first molt.

The question I have is this: How long should I expect him to hide in his hole? Will I need to dig up his hole to get at his shed carapace?

First, is your scorpion an adult?
If it is, it will have a red telson. (stinger) Scorpions do not molt once they are adults.

I've noticed that when emps are first bought, they are rather active for the first month or so, but after that they mostly stay in their burrows.

If your emp is not an adult, it could very well be in premolt. The time it takes to molt will depend on the size of the scorp, etc.

When a scorpion is in premolt, they appear very fat. Other signs of a molt are hiding more than normal and refusing food. (Note, this does not necessarily mean that the scorp will molt, emps are known to fast for long periods of time, they also spend 90% of their time in their burrows.)

You may want to read this if you have not done so already:
[ASA] Forest Scorpions' Caresheet

So he's (At least I'm pretty sure it's a he) got a milky white/yellow telson. I purchased him fresh from a local invert dealer. During his first few weeks, he'd always adventure around the tank, climbing stuff. He was largely nocturnal. Within a week he'd found his favorite hide, and would always stay there with his claws barely poking out. After a quick redecoration of his tank a week or so ago, he started coming out and being more and more active, more and more often. He also still kept the pattern of keeping just the tips of his claws exposed from his hide.

That's actually how I got that picture of him you see on my avatar.

Since that night, however, I noticed that he seemed a bit lethargic for a day, then he vanished. He's not in his normal 'hide' places, which only leads me to believe he dug himself a bit deeper into the substrate. I'm hesitant to try and 'go find him'.

It's been a few days. I'm more or less active all night, and he's got a night "moonlight" blue LED that I keep on occasionally. Even in darkness, however, quick checks still have him MIA. Hopefully, he's molting well.

UPDATE!

So, checking the humidity, I found a new burrow! He's definitely alive, AND it looks like his claws are turning a dark jade greenish color. Some vids I've seen online suggest that he's getting ready for his first (At least the ones I've witnessed) molt. Am I far off?

Not far off
Especially if you noticed that he has gain abit of "Fat" before he disappeared in his burrow.
Young scorpions of 2.instar onwards up till 5.instar has rather close molting intervals when the captive conditions are right. E.g. Between 1-4 months.

I'm not too sure about using the blue "moonlight" bulb on him. Switch to using red infra red heat lamp would be more ideal for night viewing and varing the distance to the tank adjusts temperature gradient.

Btw, if whenever suspect a molt is due, do not dig him out recklessly.
You do not wish to hurt him accidentally.

Cheers.