Assuming copulation was succesful - she may reject prey. If she does, try offering fuzzies instead of adult mice. Don't worry if she rejects those too.
6 to 8 weeks or so she will probably shed, when she goes blue, give her a nesting with moist but not wet substrate (asbestos free vermiculite, perlite, moss, coconut husk fiber work well). Try to make the nesting box as dark as possible. Make sure it doesn't dry out. She will likely lay a week to 10 days after that shed.
If you google "breeding kingsnakes" you should probably find lots of detailed information.
Where is your lavender from? Know what line it is?
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3.3.2 L. getula californiae
1.1 L. getula nigrita
1.0 Boa constrictor constrictor (suriname, fostering/rescue)
2.3 Elgaria multicarinata multicarinata