Airtable does not behave at all like a Spreadsheet (despite their advertising slogans), so you’ll have to adjust the way you think about your records a bit, but I assure you that Airtable will work great for what you are trying to do.
You cannot do “math” operations on Dates in Airtable. Airtable acts like a SQL database in handling data-types, so they provide functions for working with dates. You’ll want to use the
DATETIME_DIFF() function to find the difference between two dates.
You won’t want to do this in Airtable. Instead, use things like check boxes, or a date field to mark the date something was shipped. Then, use “Views” to filter your records to see only what you want to see in a given View. You are still looking at the same Table, which has all of your “Shipment” records (or whatever you call them), but you are filtering it down to show only those with a “Shipped” date or with the “Shipped” check box checked. You can build as many Views as you need to view different slices of your data. Try using the “Grouping” feature to group your records by those that are shipped and those that aren’t, or Group by Shipping date, or Group by Shipping month, etc. You can achieve all the same things you used to do by moving records across sheets in Google Docs by using “Views” in Airtable.
There is not a way to do this in Airtable, but I reckon once you get a handle on how Airtable works as a database rather than a spreadsheet, you can come up with other mechanisms to accomplish what you used to accomplish with these header rows.
The gist of all of that is that you have to adjust the way you think about the structure of your data when making the switch from Spreadsheets, because Airtable is a database, and not a spreadsheet.