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.
If an investor is willing to hold then he has the option to buy at any time. Especially since the current halving is only a few days away. The biggest bull run will start in 2025 so everyone holds on for that time. So since 2024 is the best time to invest in present time, all the coins prices are under control so any investor investing in present time will definitely be a good investment.
In fact if the investment plan is for the next bull season then it is better to buy at the spot price. Because we know the next bull run will start and it will reach all time highs and also if the investment plan is long term then it doesn't matter where you buy from. The bull run may begin in 2024 and may continue into 2025. So invest, keep investing, you will surely succeed. If you wait to invest without investing, you will never be successful.