Actually there is no specific time to start, but as investors, of course we have special considerations when the best time to buy, and in my opinion the faster is better, this is because the opportunity for rising can occur at any time, the usual mistake is too often doing analysis and delay to buy.
But it is not good idea to invest all your money at the time of bull run. Price can fall down any time also and for this we have to invest portion by portion. Bear market is suitable to enter the market. Here anyone can get huge opportunity to buy more with low capital.
Yes, when talking about a market going up, the sooner the better, but here I don't see any consideration when the price goes down, keep in mind that not only can opportunities go up at any time, but opportunities to go down can also occur at any time. Here talking about altcoins, when talking about bitcoin maybe I will be very optimistic.
Doing frequent analysis in my opinion is a good thing, as long as it is accompanied by buying (not not buying). However it is something important that must be done, otherwise it might be said as a rash act, for not thinking carefully before we buy.