i dont think any of us have ever seen "too ripe"... it takes a while; and trust me, you wont let them go that long
... the closest thing i have seen to a bud gone too long would be when i revegged the first time... left on a decent amount of bud for regeneration, and the bud stayed on for about 2months or better... eventually it just started to brown and fall off; but all the way untill that point, it looked damn smokeable to me
... those buds were @5-6 months old... i doubt you will let em go that long