There is no wrong if you perform Umrah first and then hajj, but since hajj is fardh on a person having capacity to go for it, so it is not right to delay it unnecessarily. Also, one never knows whether he will live or not; therefore do not delay hajj for one year as well, rather perform hajj this year. And if it is not possible, then perform hajj and Umrah in one journey.
Allah knows Best!
Darul Uloom Deoband