Sole proprietorship has to be registered by seeking a local license. If your business deals with selling goods then you need to get registered under VAT or if you're a service provider you'll get register under service tax. After registration opening a current bank account is necessary because a canceled cheque is the compulsory requirement in getting the IEC.
If you're applying for IEC application you must have documents like Copy of PAN card and ID proof, passport size photograph and copy of canceled cheque. The next step is to apply for digital signature to sign and submit online IEC application. After collecting all the required documents and digital signature, you can apply for IEC code.
No, opening of current account is not necessary for the Import Export Code Registration Certificate because if the registration is in the name of a Proprietor, savings account of the Proprietor will suffice the purpose to apply for IEC Certificate. But if one needs the Certificate in the name of the firm then it is mandatory to have a current account in the name of the business name of Proprietorship Firm.