And it shall come to pass, when ye are come to the land which Jehovah will give you, according as he hath promised, that ye shall keep this service.

When you enter the land that the LORD will give you as He promised, you are to keep this service.

and it hath been, when ye come in unto the land which Jehovah giveth to you, as He hath spoken, that ye have kept this service;

And it shall come to pass, when ye are come into the land that Jehovah will give you, as he has promised, that ye shall keep this service.