If you were simply visiting the USA as a tourist, your visa would be valid for 10 years from the date of issue. (i.e. you'd be able to enter the USA at any time during the following 10 years). It wouldn't matter at all as to whether you were planning on boarding a plane to the States on the day after you'd got your visa or in over 9 years time.
The situation is basically the same with an immigrant visa (rather than a tourist one), except that there's no time limit at all on it's validity.
Your visa application process is simply assessing whether you're acceptable for entry to the USA as a resident. It doesn't matter one iota whether you'll be travelling there just after you've got your visa or not until you're receiving your pension. The date of travel is totally irrelevant to the visa application process.