When will baby sit without support ? And when will they sit up by themselves while lying on the bed?

Abt 5-6 months for sitting and abt 7-8 for by themselves while lying on bed. Every baby is different so no need to rush. If u are concerned then try to let baby have the opportunities to do the above tasks. I will read to him storybooks when he sit up (assisted w me behind then slowly progress to at the side). Giving praises and clap hands to praise him is another way to motivate baby