In dwellings, National Electrical Code says to use 3 volt-amperes per square foot, to calculate load requirements for general lighting and general-use receptacles. So a 15 ampere circuit can cover 600 sq.ft. of general lighting and general-use receptacles.
600 sq.ft. x 3 VA = 1800 VA
1800 VA / 120 volts = 15 amperes
Since this is a dwelling unit basement, you can use the same 3 VA per sq.ft. to calculate the requirements for the receptacles in the "shop" area. However, since you're likely to use larger loads in this area, you might want to do the calculations using 180 VA per receptacle instead. For a 20 ampere circuit, this would allow 13 receptacle outlets.
180 VA x 13 = 2340 VA
2340 VA / 120 volts = 19.5 amperes
So depending on the square footage of the basement, and the number of receptacles required in the "shop". You may be fine proceeding as planned. Obviously, if there's any "special" equipment in the shop (240V loads, large equipment, etc.), you'll have to install appropriate circuits for them.
Depending on the type of shop, and what equipment you'll be using, you might not be happy with a single 20 ampere circuit. For example, if you're going to have a wood shop with a table saw and dust collection, you're likely going to want more circuits.
The finished area of the basement would require AFCI protection for the circuits. Depending on whether the shop is considered finished or not, those receptacles will require GFCI or possibly AFCI protection.