I thought I had better buy them before they sold out so I went ahead and bought some.
I was a bit worried they might sell out quickly so I decided to buy them even though it might have been a bit early.
私も良いものは早めに買うのが好きだから、翌年のクリスマスプレゼントを冬のうちに購入してしまいます笑
ーI thought I had better buy them before they sold out so I went ahead and bought some.
「売り切れる前に買ったほうが良いと思ったから、買っといた。」
sell out「売り切る」
went ahead and bought ... で「…を買うことにする」
ーI was a bit worried they might sell out quickly so I decided to buy them even though it might have been a bit early.
「すぐ売り切れたらと心配だったから、ちょっと早かったけど買っておくことにした。」
sell out quickly で「すぐに売り切る」
a bit early 「少し早目に」
ご参考まで！
カナダ 
