Just to add to Nurse2Pilot's post above, a consideration may be whether the NAA permits the issuance of a temporary certificate in accordance with ARA.FCL.215(d). Specifically, this means that after a skill test or assessment of competence for the issue of a rating or certificate, the examiner may issue a temporary certificate for up to 8 weeks validity to allow the candidate to exercise those privileges immediately after said test or AoC whilst the NAA gets round to adding the rating or certificate to the licence.
Note this would also apply to a renewal of a rating or certificate where the examiner is not able to sign the licence. Also note that this does not apply to the initial issue of a licence.
Not all NAAs permit this. Those that I know who do includes the UK, Norway and Denmark. Those who don't include Ireland and Austria, the implication being that for these countries you will have to wait for the licence to be reissued before exercising the new privileges.
Anyone wish to add to these lists?