The progress indicator is confusing. During all of the download of the signatures it will stay at 30%. After the installation of CIS it will have to download approx 104 MB worth of data… during this download it will stay at 30%. That is needlessly confusion.
To see where the download process is go to Firewall → Common Tasks → View Active Connections → now keep an eye on the cmdagent.exe and see where the download is.
When you are on a slow connection you can try:
This download supports resuming; so you can use a download manager to download it to your convenience. Keep in mind that the clean install of CIS has no. and I repeat no, AV signatures.