I am considering Endowus but it needs to start at min 10k using CPF and monthly RSP for 10 to 15 years. With current Covid-19 market conditions and going down the road, should I wait for months to see and start later?

RSP only works if you remove emotions from the plan. Add in timing and the plan will fail. Start out with what is comfortable for you, and stick to it.

If you can commit to investing consistently in the next 10 to 16 years, and to put in a significant amount relative to the $10,000 you put in ($500 or more), I dont think that starting later or earlier matters as much, because you would have put more at work.