My mom letting me go for the weekend with my boyfriend

I recently turned 18 in July I already graduated from high school and I been with my current boyfriend for about 2 months he's 21 and I took off time from work ( a weekend coming up ) to have a mini-vacation with him but I still live with my mom so i have to somehow let her know and hope she doesn't say no but apart of me feels as though I'm an adult so I should be able to then apart of me feels i still need her permission to do stuff of that sort so I really need honest opinions of how to go about this the right way so she's ok with it and let's me go my boyfriend knows how my mom is and understands the circumstances of my situation so do I let her meet him and then go ? Just ask ? Have a sit-down with my mom and explain ? Wait or don't do it ? What do I do btw I took off 9/1-9/3 and it's less than I month away I just wanna to relax and be with him for a weekend btw we're getting a hotel because he lives far from me and we're going out I can handle myself and stay smart be protected I trust him I have been out with him before just not for a weekend