If you've a large discretionary income present, it's fine to lump sum since the funds are available. Personally, I wouldn't lump sum with everything at once. I'll like to divide the money into 3 parts, lump sum with the first part, use the second part to increase my aggressiveness in DCA and keep the last part for buying my target dip.
Sound like a pretty nice idea to me, and I can easily relate with your strategy, if I really understand what you meant then I believe you're taking your time to study the situation instead of just indulging in fast purchase thereby analysing the state of the market to see if it convenient to buy more which is why you apparently divided the funds into three part, which is a also a good strategy which involves lot of monitoring and follow up to ensure timely response Incase of a possible rise or fall in order to make your decisions promptly.