In which order should I use the cassettes in the SENSE Cassette Combo packs?

WaterGuru sells 2 Combo packs:

The SENSE C2/C5 Cassette Combo pack which contains the following:

• 1 x C5 Cassette - Measures pH and FC daily, plus CYA, Hardness, and total Alkalinity, lasts 29 days
• 2 x C2 Cassettes - Measures pH and FC daily, each lasts 58 days

The SENSE C2+/C5+ Cassette Combo pack which contains the following:

• 1 x C5+ Cassette - Measures pH and FC daily, plus CYA, Hardness, and total Alkalinity, lasts 32 days
• 2 x C2+ Cassettes - Measures pH and FC daily, each lasts 64 days

How to use these cassettes after you have used the C5+ cassette that comes with the SENSE S3 or the C5 cassette that comes with the SENSE S2

The SENSE comes with a C5+ cassette (SENSE S3) or a C5 cassette (SENSE S2) which should be used initially to balance the pool's water chemistry for the first month.  
 
You have two Combo pack choices.  Either purchase a SENSE C2/C5 Combo pack which includes 1 x C5 Cassettes and 2 x C2 cassettes or a SENSE C2+/C5+ Combo pack which includes 1 x C5+ Cassettes and 2 x C2+ cassettes.  

Each Combo pack comes with a printed insert:

 
After you have used the or C5 or C5+ cassette for the first month, the use of the C2 or C2+ cassettes from the  Combo pack for the next 2 months or 4 months depending on your pool season, should be enough to keep the pool's water healthy for the remainder of the pool season.
 
Depending on where you live, nearing the end of your pool season when you need to know water chemistry values for closing the pool, you can purchase another Combo pack and use the C5 or C5+ cassette from the 3-pack to balance your pool's water chemistry before you close your pool.

Note:  For customers who require C5 /C5+ cassettes year-round for their pool water chemistry measurements, 3-packs of the SENSE C5 and C5+ cassettes are available for sale at the WaterGuru website.