With the Update 4 released last week, over the weekend I worked on how much the extra specilizations would run between getting career and non-career. Here's the math based on 5 specializations. Please note, the first Specializations isn't shown since that is a bedrock choice. The number in brackets [ ] is the number of games a player needs to participate in at 15 X/game, rounding up.
(C= Career Specialization; NC= Non-Career Specialization)
C 10
C 15
NC 40
NC 50
Total 115 [8]
C 10
NC 30
C 20
NC 50
Total 110 [8]
C 10
NC 30
NC 40
C 25
Total 105 [7]
NC 20
C 15
NC 40
C 25
Total 100 [7]
NC 20
C 15
C 20
NC 50
Total 105 [7]
NC 20
NC 30
C 20
C 25
Total 95 [7]
As you can see, going into a non-career Specialization early will be cheaper than waiting until the end. Going 6 specializations is this when dealing with Non-Career Specs
Backloading (taking the Specilization last) 60 (175) [12]
Frontloading (taking the Specialization as soon as possible; career specializations add 10 to the final count) 40 (145) [9]
Although not recommended, taking 7 Specializations looks like this:
Backloading (taking the Specilization last) 70 (245) [17]
Frontloading (taking the Specialization as soon as possible; career specializations add 10 to the final count) 50 (205) [14]
Please note, that's if you spend all XP on specializations as soon as possible. THIS IS NOT RECOMMENDED!