Something like this?
string path = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
DateTime compareDate = DateTime.Now + TimeSpan.FromDays(-6 * 30.5);
IEnumerable<DirectoryInfo> searchResults = new DirectoryInfo(path)
.EnumerateDirectories()
.Where(info => info.CreationTime <= compareDate)
.OrderByDescending(di => di.CreationTime);
foreach (DirectoryInfo info in searchResults)
{
Console.WriteLine($"{info.Name} | {info.CreationTime} | {info.FullName}");
}