I try to keep things as software independent as possible and therefore rely purely on the Windows file/folder system to keep my files organised.
30,000 is a lot of photos to organise, therefore keyword/tagging them will be incredibly time consuming and as such, personally for now, I'd just stick to organising them into folders. If you name the folders in reverse date order (Year-Month-Day Brief Description) it will automatically put them in order. In the case of an event that spans days or weeks (such as a holiday), just use the first day in the folder name.
For scanned images, it'll be a bit of a guessing game as to when the photos were taken. Kids and haircuts are quite often good indicators in order to figure out the approximate date when the photos were actually taken. For digital photos, you can see when the photos were taken from within Windows File Explorer. Click on 'View' > 'Details', and that will give you columns instead of just thumbnails. You can then add a 'Date Taken' column by right-clicking on a column and selecting it. If you click the top of that column it will arrange them all in 'Date Taken' order. You can then drag and drop them into folders and you can name the folders appropriately.
As for burning, each to their own, however I'm not a big fan of optical media and have had multiple DVD's fail over time (which were probably only about 8 years old), where they suddenly couldn't be read anymore. This included a commercial 'pressed' (rather than burnt) DVD as well, so I don't have much trust in them. There are specialist archival optical media like gold DVD's, but even then optical media is still slow, small capacity, bulky and just not as easy to work with as harddrive and solid state storage. So, given the relatively low cost of harddrives, combined with their speed, small size, large capacity, I use these. Main data drive in the computer, one on-site backup in water/fireproof safe, one backup kept off-site (which some people rotate with their on-site backup). The backups are purely of data files synced with the data drive in the machine, I don't bother backing up the OS.
There is one benefit with burning to optical media, and that is most of the time they're read-only, which means you can't accidently over-write or delete something. Therefore, be careful with harddrives as you don't want to accidently overwrite or delete an original, then sync it with your backup drive.
In the future when internet upload speeds are a lot faster, I think for most people their off-site backup will be OneDrive.