I would try to get in 6-8 weeks at peak mileage (or even more if you want!), but bring it down in the 10-15 days before your peak/most important race. Also, feel free to take slow days and days of less mileage when you body feels it needs it (and do your recovery days slow!). If you do 8ish week at 65 mpw you would start to reach peak mileage in the last week of March. Just make sure you have built up to it before you jump in.