When can an objection as to jurisdiction be raised in Court?

An objection to jurisdiction can be taken anytime in court. Either on the basis of statement of claim, writ of Summons, evidence received or by motion on notice supported by affidavit giving facts upon which reliance is placed.

The important factor is the materials before the court and if it can help the court determine the aspect of jurisdiction raised.

Carnaud Metal Box (Nig) Plc v. Agwele (2011) ALL FWLR (pt.609-805) page 750 at 761, paras D-F.
Adeyemi v. Nnadozie (1952)14 WACA 361. Elabanjo v Dawodu (2006) ALL FWLR (pt. 328) 604 SC.