I think the psychiatric symptoms can come about at any time, from shortly after the bite to years later.
Here is a link to a symptom list:
http://www.canlyme.com If it doesn't show up, click on "symptoms" on the left and scroll down.
Apparently, the tests done for Lyme are not very accurate so some doctors diagnosis Lyme clinically.
I'm looking into this for my difficult child/easy child because of her physical symptoms but looking back, she did start having psychiatric symptoms about 3 months after she had a suspicious bite.
The good news in there is that frequently with long term antibiotic treatment, the neuropsychiatric symptoms improve.
A good book about this is "Coping with Lyme Disease: A Practical Guide to Dealing with Treatment and Diagnosis" by Denise Lang.
ETA: The book is about Lyme in general with one chapter about the psychiatric problems.