It depends how quickly the executors get a grant of probate. They get that by having the whole estate valued and paying what the Revenue accept as a suitable payment of inheritance tax to be going on with. Once they have got that,they can distribute the estate in accordance with the will. If the bequest is only a modest cash sum in relation to what the estate is worth and has in cash, you'll be paid as soon as probate is granted and if it's a specific bequest ("the green vase with HR on it" etc) you'll get it straight away in nearly all cases.
Even so, that may be some months after the death.