I’d think any cap that you bought off the shelf would have been in a discharged state for a long period, however if kept in circuit with a battery
(and if both are coupled on the same side of the key switch) The cap would be kept charged for a reasonable length of time until the battery
was drained or the fuse removed from the cap (granted I don’t know how long the cap would hold a charge for in a disconnected state???
Thinking that caps and ignition condensers are much the same thing, I’ve had ignition condensers with the 1970 stamping on them work better than brand new condensers