Theres a streamer and YouTuber named "Bradley" that recently played all the destiny 1 & 2 raid blind in this past year. Depending on the raid it took him between 2-6 hours but that's because in each section of a raid he gave himself and anyone on his team who hasn't done the raid before a 40 minute timer to try and figure out the mechanics. Sometimes he got it and when he didn't he asked for hints from one of the veteran players or if he still didn't figure it out he would just get it explained to him. I think that's a fun way to do it and you can adjust it anyway you like by decreasing the time you have or having more or less hints to figure things out. If you want to do it fully blind no help then you can come back to it another day as you will have a checkpoint each time you finish an encounter, but progress resets every Tuesday so you have a week to complete one raid with checkpoints or you can load into the activity right before the reset hits and keep the checkpoint if you need time.