I was going through the sentences and explanations of "言っておく" when "言っておくと" caught my eye. It repeatedly showed up as an alternative to "言っておくけど". I think けど here is somewhat like "you know" in English. But as for と I really can't think of any usage that could fit in with the sentence. (Not if/when/quotation, definitely not and/with, and then I am baffled...)
言っておくと、私明日来ないからね
言っておくと、あいつ俺の妹だからね。
言っておくけど、ロスでは車が必要だよ。