Is this really the case?
It doesn't matter how long you've used your wallet. Even the time passed since sending the transaction is not just some fixed minutes, it depends on many factors (from luck to say so, since a block may be mined within seconds from you sending the transaction to even an hour sometimes, to the fee used for the transaction and the number of others' transactions not mined yet).
But more clearer, all that matters is whether a miner has managed to put that transaction of yours into a block or not.
Electrum will show that as confirmations. If (and only if) you have 0 confirmations for your transaction then yes, you may cancel it (meaning to send it to yourself instead of somebody else).