i say TRY it. see if it feels okay in the first few hours of ur day and if it doesn't, pivot! go outside, get ur favorite drink or watch ur favorite movie. i treat birthdays as a personal ritual. what do i love??? what do i wanna do on a perfect day??? incorporate that idealogy into your time and know that alone birthdays are no less special. if anything, it's a day to reset/realign and esp for a 20th!! think about what u wish and hope for in this new decade of life. and than whenever ur friends get back, throw the most fun party <3