New at version 14, there are fields you can populate during the manual creation of a Fixed Asset that will be used to create a partial depreciation schedule (what is remaining):

If you have a $2,500 computer hardware Fixed Asset purchased on Jan 15th, 2020 with a salvage value of $500 that you are straight line depreciating over 36 months and start using Odoo at the beginning of the 14th month (so expect to see a depreciation entry at the end of February 2021), you can enter the previous depreciation this way:

1 - the dollar amount previously depreciated
2 - the amount of months previously depreciated
3 - the first date of the previous depreciation
4 - the calculated remaining depreciation based on 1,2 and 3
5 - the remaining amount of months to depreciate in Odoo
6 - when to start the remaining depreciation in Odoo
Be sure to review the documentation at https://www.odoo.com/documentation/user/14.0/accounting/payables/supplier_bills/assets.html to understand how you can use Asset Models to make it easier to bring in Fixed Assets with the same "types" of depreciation (method, duration, etc).
Note: If working with a version prior to v14, you would create the Fixed Asset as if the entire depreciation schedule would be posted in Odoo, but delete the first 13 entries before confirming the creation of the Asset.
Is there a possibility to import Fixed assets? We have implemented Odoo 13 and have +/- 1000 lines of fixed assets that are partly depreciated. At the moment they are maintained in Excel.
Manually adding these line by line will take a very long time. I have seen some import manuals but these are without value and only and import of the ID/Name.
Sam:
Try to manualy create some assets (Menú: Accounting / Accounting / Assets)
Then, from the list view, export them to Excel (check the checkbox in the header -all lines checkboxes will become marked- and execute Action-Export) Choose at least the mandatory fields from the available ones.
Use that Excel document as a template. Populate the proper columns and import them from the same list view.
My advice is to make a test with a few lines in a test database.
This procedure is useful to import data to almost all classes in Odoo.