Deductions & credits

Ok.  He also remodeled a second unit but has never invoiced me for it but I do have the estimate in writing for a little over $15k.  

 

I could use the estimate but if his final number is different then I'm in trouble.  

 

If I choose not to depreciate until he actually notifies me the amount by invoice then is this first year lost or do I just start the depreciation from when I found out the final balance?  Unit has been in service since November.