Confirm from my own experiece that referrals can't be added after the accounts are active as @srlawren said and he also made good point that savings are worth gettng the plan.
You will still be eligible for auto pay discounts ($2/30days or $6 per 90 days of plan), community rewards (varies with $1 - 2/mo fairly easy with some community activity), loyalty rewards ($1/mo for every year you stay up to 5 max) and of course other referrals in the future. And so far no price increases -yeah.
My own referral experience where referrals could not be added after referral account was added was when my own port didn't work properly.
I had an active account with a ported number (but not the # I intended). I used that # when I added my wife to PM. Unfortunately the only way to fix my situation (ported wrong number which I wanted to return/ port back to original landline) & keep the 4G plan was for MODs to change the account, which I didn't realize at the time meant loosing the referal rewards. It was fine as I wanted to get both cells on PM plan & wanted to keep landline number where it was, and the MOD's were kind enough to offer a one time credit to offset the loss of referral after they tried & unable to add the referral from the previous account over to new account.
Other than that little hiccup at the start we have both loved the PM plan & savings, reception, reliability & even used the new-ish USA addons.
