Sorry to resurrect this old topic but I had to thank Riamus2 for indirectly answering my question before I asked it and adding something to it.
I have been away from mIRC for a while but have started to get back into it as I recently purchase 16 copy site license for my Students Computer Lab and wanted to re-learn it before introducing them to it. I find that I have forgotten much that I knew but did remember enough to reload some of the saved scripts I used to use often.
One of the things I could not recreate was having multiple channels open at once with only one of them maximized. I had to almost follow your advise. What I ended up doing was, I stopped my login attempt before I went to any channels, maximized the Network Status window, Right-clicked on the Network status button, and selected Position\Save.
I then closed the mIRC window, restarted and allowed the login to complete and everything was maximized, just like I wanted it to be.