According to the ADK trail guide, the Blueberry LT is 4.5 miles from the TH, and Ward Brook LT is 5.4 miles. You can figure your time by dividing by your miles per hour pace (this is an almost-flat easy trail). Some 60 year olds are faster than some 50 years olds, or even some 20-40 year olds. Age is not necessarily a handicap, though lack of fitness can be.
Seymour from Ward Brook LT is 1.5 miles but almost 2000 ft ascent--very steep. A slow pace would be 2 hours to the top (1000 feet per hour; 0.75 mph). Some people are faster descending, some are slower.
S-D-E is 4.4 miles one way and 3100 ft ascent (1150 ft ascent coming back). 1 to 1.5 miles per hour is a reasonable pace on these herdpaths.
The Sewards are a wonderful place--enjoy them!