So I used the OBMM BSA time reset option and now all my BSA's are the same date.
Can I use a redater and change the time to increase a couple of BSA's by minutes?

Yes, you should do this.

Should the official mods and the SI expansion BSA's be dated after the oblivion BSA's dates?

If you don't have any BSAs that replace anything it doesn't matter.

If you do have such BSAs, those BSAs need to be set to a later date than the files they replace in the data\* folders.

EDIT:

Any BSA that doesn't replace anything should IMO be set to 01-01-2006, this makes sure that files in the data\* folders have a later date and will replace the file in the BSA.

No. The different DLCs' BSAs and the original BSAs have nothing to do with one another. There are many people with the DLCs installed that do not think twice about unofficial mods and BSAs. There is no need for them to do so...

Cybiades uses 6 BSA's, should they all be dated the same?

Also, if many BSA's are dated the same, would that cause problems?

No. A mod should not be packed such that BSAs for the same mod contain overlapping files. HoD is certainly not packed that way. The names of the BSAs usually indicate that. As long as the BSAs do not contain overlapping files, the dates for every BSA could be the same.

You are probably better off using a file redater to redate whichever BSA actually needs the date change. With most users' modified setups, the BSA timestamps are not a cause for trouble at all. If you do not mess with the original BSAs after they are installed, all of the Vanilla file replacers will work.

I don't know what the Cybiades contain, so follow the install instructions.

The only "official" MOD bsa that I know of that require a specific date is MMM.bsa, it needs to have a date later than all files installed before it, and if you have any replacers (eg. texutures) for MMM (loose files) they need to be dated later than the MMM.bsa.

If you make your own BSAs, or download a BSA for eg. OOO, Warcry or similar, the same is true for those.

Thanks to all of you.