Isn't it 1,000 miles and/or free supercharging for a year?
In fact, if you're pretty certain you'll take delivery before the end of 2020 to get the 1 year free supercharging, it makes sense actually to use someone that already has a Tesla since supercharger miles expire 6 months after getting them. There will be no way you can use them, except for between now and Dec 31st...
Edit: Ok, you'll each have made a referral plus the base miles you get for having used someone's code. I'm really surprised Tesla brought back the option to add codes after you've ordered, they were very stringent about that for awhile. I hate that I missed out on a referral now because the guy called in after he ordered online to have his sales guy add the code