Welcome to the fraternity.
Any target that you consider to be reasonable and achievable, is a good target.
My best advice if these are your first two days on a bike since childhood, is to not pay attention to any of the talk on here about distances and speed. Enjoy going for rides. If numbers motivate you, great. I would recommend you compare to yourself. In that way you're more likely to see consistant positive reinforcement and less likely to get discouraged by not catching up to riders who have decades of experience in the saddle.
It's tough for beginners to know whether bottom discomfort is because of saddle selection, position or need for the body to acclimate to the new activity. Generally speaking, no matter how well selected or positioned the saddle is, anyone's bottom is going to be sore when they first begin cycling. Repeated Time In The Saddle (TITS) is what is required to overcome this. However, if at any point you experience genital numbness or accute discomfort, something should be done to address this issue. Don't ignore that.
My bike is the best drug I ever got addicted to. I fall off the wagon from time to time. Enjoy exploring the world without windows and AC;-)
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Birth Certificate, Passport, Marriage License Driver's License and Residency Permit all say I'm a Fred. I guess there's no denying it.