[shorod]

Do you happen to have the defroster or air conditioning on when you start it in the morning? If so, you are probably correct that the noise is a belt. Well, you are probably correct that the noise is a belt anyway. If you have the defroster or A/C on though, that would help explain the cyclic nature of the squeal. Defrost will also engage the A/C compressor (to remove the humidity from the air) and assuming your A/C system is properly charged and the ambient temperature is above freezing, the added load may be causing your belt to slip and squeal.

Inspect the idler pulley and self tensioner for wobble and bad bearings. If they look fine, then replace the belt. I'd suggest using either a Kelly-Springfield or Gates belt. From my experience, Dayco belts tend to stretch and squeal and Goodyear belts often times are noisy.

-Rod