The best time to increase SP is whenever you are able to increase SP.
There are simply a ton of benefits to having more SP at your disposal.
SMT released tokens, one the protocol is finished might come out rapidly. There is no telling how many will be created in a week or a month.
Plus as was mentioned by @robert-call, the app creators take a snapshot of the blockchain at different points....they might not use the information from a week before the release...they might use a block two months old.
I wouldnt try to rig the system.
Let see...