gte747e

I'm sailing on Harmony in Aug 2018. When is the best time to purchase photo packages? My extended family is spread over 4 cabins. Last time I purchased the all included USB stick and I was happy with that. Prints aren't as important for me, but are a plus. Any advice on what to purchase and more importantly when? Online says save 20% over onboard prices, but I know sometimes they run specials on board (especially early in the cruise). Thank you so much for any help you can provide!