1 TB or 2 TB Fusion Drive?

Hello, I just purchased the IMAC 27 intel core 3.2 GHz Core i5 memory 8 GB 1867 MHz DDR3 AMD Radeon R9 M390 2048 MB OS X El Capitan version 10.11.1 .

The question I have is in regards to the fusion drive. Is it worth roughly an extra $300 to upgrade to the 2 TB fusion drive from apple to get the extra 128 gb SSD ? Or should I wait and attempt to upgrade 1 TB fusion drive with an aftermarket SSD at a later time or Should I go and pay the $300.

The sales associate at Apple gave me incorrect information when I purchased the computer. I was told the fusion drive was configured with 128 gb SSD, which it only comes with 24 gb SSD.

FYI. I am using this computer for personal use and doing some low key video editing with iMovie and GO pro.

Thank you for the help and advice.

Chris