If subtle bodies (which are not in physical bodies) are beyong time and space how do they accumulate Karma to fructify?
There are infinite number of Jeevas (living beings). They have three bodies. Causal Body, Subtle Body and Physical body. Only when they have all three bodies they live in one of the 14 lokas. Only when they live here in earth AS HUMAN BEINGS, they can accumulate karma.
Since creation is a cycle which is beginningless, the infinite number of jeevas have accumulated karma when they lived as human beings in earth. Since they have born infinite number of times, invariably they have born in earth to accumulate Karma.
There is no first creation since creation is beginningless. So there is no first birth as human being.
Jeevas keep taking physical bodies to exhaust the fruits of their karma. Until that happens the cycle of birth-death will not stop. Death happens when the fructifying karma (Prarabdha Karma) gets over. That time physical body is gone. Jeevas will continue with subtle bodies awaiting the fructification of next set of karma to be born again. This cycle continues until one gets liberation.
When the creation comes to an end even subtle bodies are destroyed. Jeevas will have only Causal Body which is the store house of all past karmas. When the cumulative karma of all the jeevas is ready for fructification, the next cycle of creation starts. This cycle will continue forever since the number of jeevas are infinite.
Time and space have meaning only when the jeeva has a physical body. So questions such as "after death WHERE does the subtle body resides OR HOW LONG it will wait for the next birth?" are meaningless.
Thanks for asking this question and if you need more clarifications, please do ask.