Use the Parent property in the UserControl_Show event

Let me confirm about the Parent property of an ActiveX control, UserControl created with VB6.0. Assume that the container would be IE5.0 SP2 or higher.

Now I have a question regarding with the usage of the Parent property in the UserControl_Show event.
I am aware that the UserControl_Show event allows me to get Parent as a MSHTML.HTMLDocument type object. Using this, I wrote code so that it can retrieve the value of the HIDDEN field in HTML like below:

Parent.parentWindow.document.Forms.Item("FORM‚ÌID").Item("HIDDEN‚ÌID").Value

I have already confirmed that this is possible and work well.

What I would like to ask is:

When the Parent property is used in the UserControl_Show event, can I assume that HTMLDocument of the container IE has been completely loaded?
I mean, can I assume the case, which the UserControl_Show event fires while HTMLDocument is being loaded and this causes the unloaded HIDDEN field to be refered, leading to an error, never occurs?

Is there anyone who can help me out?