I always thought the Show Stable and Pretty Parlor were introduced in Year 2 (1984), but here they are in the 1983 Sears Wishbook alongside the Collector ponies! (And reissued My Pretty Pony.)
This does make sense since both playsets have references to the Collector ponies. Their symbols are on the flags of the Show Stable and the Pretty Parlor has name tags for the Collector ponies.
Also, there's a rare flat-foot version of Peachy. The flat foot Collector pony mold, the earliest one, had a tendency to fall on its nose so somewhere in the middle of Year One it was replaced with the similar looking but less tippy concave foot mold. Which points to some Peachy's being produced quite early. By Year 2 the flat foot pose was totally phased out.