How long after being added as an authorized user, will I have a FICO Score?

[Anonymous]

Hey Everyone, 

about 2 months ago I was added to my dad's BOA Credit Card (10+ Yr account) as an authorized user. I also got a credit card under my name about 2 weeks later. I'm just wondering how long is it going to take for me to have a credit score. I've read that you need an account that has been open for about 6 months. But does that also apply to someone being added to a previously existing account?  BOA already reported this account to my credit report and I signed up for MyFico's Ultimate 3B package and it generates a 700+ score since my dad has really good credit. Is this legitimate? 

Thanks for your help. 

[Anonymous]

I added my fiance as an AU to 3 of my credit cards, bare in mind she had 0 credit history before this.

I checked her scores I think about 2 months later and she was rocking a 750. So it might of been even sooner than that.

Don't see why it would take any longer than a month as the accounts backdate to how long you have had them etc.