Is it true that it takes about a week of visual/overt primary genital herpes lesions until the inguinal lymph nodes swell up?

Usually quicker: With initial genital herpes, node inflammation usually starts within 2-3 days of lesion onset. Maybe a week, but not usually. Some cases never get node inflammation, especially if the infection isn't truly primary -- i.e. if previous HSV1, the first episode of genital HSV2 often is milder without inguinal node involvement. I hope a swab test was done to document HSV from lesion and virus type.